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Yuming Jiang

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Papers by Yuming Jiang

Fair airtime allocation for content dissemination in WiFi-direct-based mobile social networks

The vast penetration of smart mobile devices provides a unique opportunity to make mobile social ... more The vast penetration of smart mobile devices provides a unique opportunity to make mobile social networking pervasive by leveraging the feature of short-range wireless communication technologies (e.g. WiFi Direct). In this paper, we study local content dissemination in WiFi-Direct-based mobile social networks (MSNs). We propose a simple GO-coordinated dissemination strategy, as WiFi Direct does not originally support content dissemination. Due to mobility and the short transmission range, the duration of nodes in contact tends to be limited and consequently they compete for the limited airtime to disseminate their own data. Therefore, fair allocation of the limited airtime among the nodes is required. We focus on fairness in content dissemination rate, which is a key applicationlayer metric, rather than fairness in throughput or airtime and formulate the allocation problem as a generalized Nash bargaining game wherein the nodes bargain for a share of the limited airtime. The game is proved to have a unique optimal solution, and an algorithm with low complexity is designed to find the optimal solution. Furthermore, we propose a detailed scheduling approach to implement the optimal solution. We also present numerical results to evaluate the Nash bargaining based allocation and scheduling.

format_quoteIntroduces a game-theoretic approach for airtime allocation in WiFi Direct MSNs, maximizing social welfare and ensuring fairness among nodes.format_quote

System Spectral Efficiency and Stability of 3G Networks: A Comparative Study

CDMA2000, WCDMA and WiMAX are three widely used 3G technologies. Since they share the same goal, ... more CDMA2000, WCDMA and WiMAX are three widely used 3G technologies. Since they share the same goal, which is to provide broader coverage and higher throughput in 3G networks, an impartial comparison of their performance is indispensable. However, they are based on different design principles and methodologies, which make the comparison challenging. This paper presents a comparative study of these technologies, with focus on system spectral efficiency and stability in 3G networks. Specifically, the paper presents a framework for the comparison based on the common set of configurations adopted by these technologies, which include channel models, system parameters and key algorithms. Through extensive simulations, the system spectral efficiency and stability of CDMA2000 1x EV-DO Rev.A, WCDMA HSDPA/HSUPA and Mobile WiMAX are compared. It is found that while WiMAX can provide highest throughput, the two CDMA-based technologies achieve higher system spectral efficiency, especially on the downlink. Regarding system stability, it is observed that CDMA2000 1x EV-DO Rev.A can operate under higher interference levels than WCDMA HS-DPA/HSUPA and Mobile WiMAX. In addition, the comparison on system spectral efficiency between CDMA2000, WCDMA and WiMAX is also conducted when relevant enhanced technologies, i.e., MIMO and interference cancelation, are adopted. We believe that our work will serve as a cornerstone for a fair comparison between the various technologies for prospective 3G networks.

Modeling and Analysis of the Survivability of an Infrastructure-Based Wireless Network

Lecture Notes in Computer Science, 2012

This paper focuses on survivability modeling to characterize the transient behavior of an infrast... more This paper focuses on survivability modeling to characterize the transient behavior of an infrastructure-based wireless network in the presence of disastrous failures and repairs. Two modeling approaches, an exact model and an approximate product-form model are presented. Numerical experiments with the two models demonstrates that the approximative product-form approach obtain close to exact results with a significant lower computational complexity. The product-form approach has been applied to study the impact of various system parameters on the survivability of the studied network.

Editorial: Special Issue on “Wireless Future”

Wireless Personal Communications, Jul 26, 2008

It was the fourth conference in series and provided a platform for wireless communication researc... more It was the fourth conference in series and provided a platform for wireless communication researchers and technologists to identify and discuss technical challenges and business opportunities in the area of wireless communications. Wireless communications is in the focus of a new and passionate era for telecommunications characterized by the convergence of systems and technologies, a transition towards all-IP networks, and the development of user-centered technologies. Wireless communications is far more than mobiles and 3G systems. It is reshaping the way we communicate and comes in all shapes, sizes, and applications, ranging from wide-area WiMAX to localarea Wi-Fi, from short range UWB and RFID to personal-area Bluetooth and ZigBee, from mobile ad hoc to wireless sensor networks, from broadband to cognitive radio, and from GPS and navigation to emerging machine-to-machine (M2M) and object-to-object (O2O) applications. This paradigm is fascinating in many aspects. It is not only about connecting people anytime anywhere, but also about connecting machines or objects to each other. Wireless communications is opening up a new horizon of possibilities and applications that will change the way we live, work and, of course, communicate in the future. This special issue is based on a selection of the best papers presented at the ISWCS'07. Among them nine papers have been selected, including one awarded paper. All selected papers were then revised and re-submitted before they underwent the usual peer-review process. This special issue presents the result of the stringent selection process in form of nine high-quality papers, covering a large range of topics from physical layer to higher layer issues. The first paper, "A Study of the Influence of Shadowing on the Statistical Properties of the Capacity of Mobile Radio Channels," by G. Rafiq and M. Pätzold, is a fundamental research paper that investigates the influence of shadowing on the statistical properties of the channel capacity. It is shown that the shadowing effect influences significantly the variance and the

Non-Asymptotic Delay Bounds for Multi-Server Systems with Synchronization Constraints

IEEE Transactions on Parallel and Distributed Systems, Jul 1, 2018

Multi-server systems have received increasing attention with important implementations such as Go... more Multi-server systems have received increasing attention with important implementations such as Google MapReduce, Hadoop, and Spark. Common to these systems are a fork operation, where jobs are first divided into tasks that are processed in parallel, and a later join operation, where completed tasks wait until the results of all tasks of a job can be combined and the job leaves the system. The synchronization constraint of the join operation makes the analysis of fork-join systems challenging and few explicit results are known. In this work, we model fork-join systems using a max-plus server model that enables us to derive statistical bounds on waiting and sojourn times for general arrival and service time processes. We contribute end-to-end delay bounds for multi-stage fork-join networks that grow in O(h ln k) for h fork-join stages, each with k parallel servers. We perform a detailed comparison of different multiserver configurations and highlight their pros and cons. We also include an analysis of single-queue fork-join systems that are nonidling and achieve a fundamental performance gain, and compare these results to both simulation and a live Spark system.

Capacity Limits for a Cognitive Radio Network under Fading Channel

Springer eBooks, 2011

In this paper, performance evaluation of a cognitive radio network is conducted. The analysis is ... more In this paper, performance evaluation of a cognitive radio network is conducted. The analysis is based on stochastic network calculus. The system is supposed to work in a Time Division Multiple Access(TDMA) mode with fixed slot length. The wireless channel is modeled as a Gilbert-Elliott (GE) fading channel, where the channel quality transits between state ON and state OFF according to a Markov chain. Spectrum sensing errors, which can be classified into mis-detection and false-alarm, are taken into consideration. Particularly, a stochastic arrival curve for spectrum sensing error process, and a stochastic service curve for GE channel, are derived. In addition, performance distribution bounds are obtained based on stochastic network calculus. Furthermore, numerical calculations are made to show the capacity limits under delay constraints.

Towards a system theoretic approach to wireless network capacity in finite time and space

In asymptotic regimes, both in time and space (network size), the derivation of network capacity ... more In asymptotic regimes, both in time and space (network size), the derivation of network capacity results is grossly simplified by brushing aside queueing behavior in non-Jackson networks. This simplifying double-limit model, however, lends itself to conservative numerical results in finite regimes. To properly account for queueing behavior beyond a simple calculus based on average rates, we advocate a system theoretic methodology for the capacity problem in finite time and space regimes. This methodology also accounts for spatial correlations arising in networks with CSMA/CA scheduling and it delivers rigorous closed-form capacity results in terms of probability distributions. Unlike numerous existing asymptotic results, subject to anecdotal practical concerns, our transient results can be used in practical settings, e.g., to compute the time scales at which multi-hop routing is more advantageous than single-hop routing.

A Probabilistic Bound for Peak Age of Information Guarantee

arXiv (Cornell University), Aug 5, 2022

This paper considers the distribution of a general peak age of information (AoI) model and develo... more This paper considers the distribution of a general peak age of information (AoI) model and develops a general analysis approach for probabilistic performance guarantee from the time-domain perspective. Firstly, a general relationship between the peak AoI and the inter-arrival and service times of packets is revealed. With the help of martingale theory, a probabilistic bound on the peak AoI is then derived for the general case of endogenous independently and identically distributed increments in information generation and transmission processes. Thereafter, the application of the obtained bound is illustrated with the M/M/1 and D/M/1 queuing models. The validity of the proposed bound is finally examined with numerical results.

format_quoteA general probabilistic peak AoI model is formulated without assumptions on information generation or transmission processes, using martingale theory for bound derivation.format_quote

On the Validity of the Decoupling Assumption for Analyzing the 802.11 MAC Protocol

Performance evaluation of the 802.11 MAC protocol is classically based on the decoupling assumpti... more Performance evaluation of the 802.11 MAC protocol is classically based on the decoupling assumption, which hypothesizes that the backoff processes at different nodes are independent. A necessary condition for the validity of this approach is the existence and uniqueness of a solution to a fixed point equation. However, it was also recently pointed out that this condition is not sufficient; in contrast, a necessary and sufficient condition is a global stability property of the associated ordinary differential equation. Such a property was established only for a specific case, namely for a homogeneous system (all nodes have the same parameters) and when the number of backoff stages is either 1 or infinite and with other restrictive conditions. In this paper, we give a simple condition that establishes the validity of the decoupling assumption for the homogeneous case. We also discuss the heterogeneous and the differentiated service cases and show that the uniqueness condition is not sufficient; we exhibit one case where the fixed point equation has a unique solution but the decoupling assumption is not valid.

format_quoteShows that both MONOtonicity and Mild INTensity guarantee uniqueness of the FPE solution, simplifying analysis of wireless networks.format_quote

A Statistical Property of Wireless Channel Capacity: Theory and Application

Performance evaluation review, Mar 20, 2018

This paper presents a set of new results on wireless channel capacity by exploring its special ch... more This paper presents a set of new results on wireless channel capacity by exploring its special characteristics. An appealing discovery is that the instantaneous and cumulative capacity distributions of typical fading channels are lighttailed. An implication of this property is that these distributions and subsequently the distributions of delay and backlog for constant arrivals can be upper-bounded by some exponential functions, which is often assumed but not justified in the literature of wireless network performance analysis. In addition, three representative dependence structures of the capacity process are studied, namely comonotonicity, independence, and Markovian, and bounds are derived for the cumulative capacity distribution and delay-constrained capacity. To help gain insights in the performance of a wireless channel whose capacity process may be too complex or detailed dependence information is lacking, stochastic orders are introduced to the capacity process, based on which, comparison results of delay and delay-constrained capacity are obtained. Moreover, the impact of self-interference in communication, which is an open problem in stochastic network calculus (SNC), is investigated and original results are derived. These results complement the SNC literature, easing its application to wireless networks and its extension towards a calculus for wireless networks.

Fundamentals of the Backoff Process in 802.11: Dichotomy of the Aggregation

IEEE Transactions on Information Theory, Apr 1, 2015

This paper discovers fundamental principles of the backoff process that governs the performance o... more This paper discovers fundamental principles of the backoff process that governs the performance of IEEE 802.11. A simplistic principle founded upon regular variation theory is that the backoff time has a truncated Pareto-type tail distribution with an exponent of (log γ)/ log m (m is the multiplicative factor and γ is the collision probability). This reveals that the per-node backoff process is heavy-tailed in the strict sense for γ > 1/m 2 , and paves the way for the following unifying result. The state-of-the-art theory on the superposition of the heavytailed processes is applied to establish a dichotomy exhibited by the aggregate backoff process, putting emphasis on the importance of time-scales on which we view the backoff processes. While the aggregation on normal time-scales leads to a Poisson process, it is approximated by a new limiting process possessing long-range dependence (LRD) on coarse time-scales. This dichotomy turns out to be instrumental in formulating short-term fairness, extending existing formulas to arbitrary population, and to elucidate the absence of LRD in practical situations. A refined wavelet analysis is conducted to strengthen this argument.

Non-Asymptotic Delay Bounds for Multi-Server Systems with Synchronization Constraints

arXiv (Cornell University), Oct 20, 2016

Multi-server systems have received increasing attention with important implementations such as Go... more Multi-server systems have received increasing attention with important implementations such as Google MapReduce, Hadoop, and Spark. Common to these systems are a fork operation, where jobs are first divided into tasks that are processed in parallel, and a later join operation, where completed tasks wait until the results of all tasks of a job can be combined and the job leaves the system. The synchronization constraint of the join operation makes the analysis of fork-join systems challenging and few explicit results are known. In this work, we model fork-join systems using a max-plus server model that enables us to derive statistical bounds on waiting and sojourn times for general arrival and service time processes. We contribute end-to-end delay bounds for multi-stage fork-join networks that grow in O(h ln k) for h fork-join stages, each with k parallel servers. We perform a detailed comparison of different multiserver configurations and highlight their pros and cons. We also include an analysis of single-queue fork-join systems that are nonidling and achieve a fundamental performance gain, and compare these results to both simulation and a live Spark system.

End-to-End Stochastic QoS Performance Under Multi-layered Satellite Network

Communications in computer and information science, 2017

To meet the growth of real-time and multimedia traffic, the next generation of satellite networks... more To meet the growth of real-time and multimedia traffic, the next generation of satellite networks with a guarantee of quality of service (QoS) is indeed, urgent. In this paper, we support the multi-layered satellite network as the scenario, owing to dynamic topology and distinct classification of the generated traffics. We map the satellite network system into a tandem queuing model, which the purpose is devoted to use a mathematical tool for evaluating the performance bounds of per-flow end-to-end networks. For delay-sensitive traffics, we compare two different arrival models-Poisson process and self-similar process. Meanwhile, we apply traditional scheduling strategy to MEO nodes while considering link impairment between a pair of satellites. Finally, we analyze, in a numerically way, which parameters (and how they) influence the perflow end-to-end performance bounds. Our analysis can be used as a reference to China's future satellite topology and routing algorithms designed and, optimization given a network with performance requirements and constraints.

Pay-Burst-Only-Once in Real-Time Calculus

Real-Time Calculus (RTC) is a powerful framework for modeling and analyzing complex networked rea... more Real-Time Calculus (RTC) is a powerful framework for modeling and analyzing complex networked real-time systems. RTC builds up on and shares many similarities with Network Calculus (NC), but some concepts are not completely the same in RTC and NC. One of the most important properties in NC is pay-burst-only-once, which can improve the precision of end-to-end performance analysis. Naturally, people would expect the pay-burst-only-once property to also hold in RTC. In fact, some existing work has used it in some performance analysis problems. Unfortunately, the pay-burst-only-once property has never been proved in RTC. There are even some results seeming to be against the pay-burst-only-once property in RTC. In this paper, we prove that the pay-burst-only-once property indeed holds in RTC.

format_quoteHighlighted that the pay-burst-only-once property was assumed but never proved in RTC, challenging previous applications of the concept.format_quote

Link-Based Fair Aggregation: A Simple Approach to Scalable Support of Per-Flow Service Guarantees

Springer eBooks, 2004

To support service guarantees in packet-switched networks, three approaches have been proposed. T... more To support service guarantees in packet-switched networks, three approaches have been proposed. They are the Stateless Core (SCORE) approach, the lntegrated Services (lntServ) approach, and the Differentiated Services (DiffServ) approach. The granularities of service guarantees provided by these approaches at each router are respectively packet level, flow level, and class level. In this paper, we propose a novel approach, called Link-Based Fair Aggregation (LBFA) approach to scalable support of service guarantees. While the granularity of service guarantees supported by LBFA is link level at each router, we show through analysis that the proposed LBFA approach can achieve as good as or even better per-flow service guarantees than the current three approaches.

format_quoteThe LBFA approach aggregates flows at each link, preserving service guarantees through effective traffic class aggregation.format_quote

Towards Optimal Distributed Node Scheduling in a Multihop Wireless Network through Local Voting

arXiv (Cornell University), Jan 31, 2017

In a multihop wireless network, it is crucial but challenging to schedule transmissions in an eff... more In a multihop wireless network, it is crucial but challenging to schedule transmissions in an efficient and fair manner. In this paper, a novel distributed node scheduling algorithm, called Local Voting, is proposed. This algorithm tries to semi-equalize the load (defined as the ratio of the queue length over the number of allocated slots) through slot reallocation based on local information exchange. The algorithm stems from the finding that the shortest delivery time or delay is obtained when the load is semiequalized throughout the network. In addition, we prove that, with Local Voting, the network system converges asymptotically towards the optimal scheduling. Moreover, through extensive simulations, the performance of Local Voting is further investigated in comparison with several representative scheduling algorithms from the literature. Simulation results show that the proposed algorithm achieves better performance than the other distributed algorithms in terms of average delay, maximum delay, and fairness. Despite being distributed, the performance of Local Voting is also found to be very close to a centralized algorithm that is deemed to have the optimal performance.

Performance Guarantees in Quantum Key Distribution Networks

This paper aims to present a mathematical tool useful for quantum key distribution network config... more This paper aims to present a mathematical tool useful for quantum key distribution network configuration. In particular, the paper studies the throughput of secret key distribution in a quantum key distribution network with trusted repeaters. In addition, the backlog of secret keys at a trusted repeater is also investigated. The analysis is based on the queueing principle of secret keys in the trusted repeater, implied by that the transmission of secret keys in the network is store-andforward. The obtained results are applied to a discrete-variable protocol with weak coherent pulse sources, where realistic system parameters are integrated in the analysis. It is shown that, if the secret key rates on the transmission path are different, the transient throughput of secret key distribution through the network also vary, located between an upper bound and a lower bound on the secrete key distribution rate.

A Hidden Resource in Wireless Channel Capacity: Dependence Control in Action

arXiv (Cornell University), Apr 30, 2018

This paper aims to initiate the research on dependence control, which transforms the dependence s... more This paper aims to initiate the research on dependence control, which transforms the dependence structure of a stochastic process in the system through dependence manipulation, to improve the system performance. Specifically, we develop a dependence control theory for wireless channels, focusing on three principles in dependence control: (i) the asymptotic decay rates of delay and backlog in the system are the measures for dependence comparison and ordering, (ii) the dependence in the arrival process and the service process have a dual potency to influence the system performance, and (iii) the manipulation of the dependence in the free dimensions of the arrival or service process transforms the dependence structure of the arrival or service process. In addition, we apply the theory to the Markov additive process, which is a general model for a class of arrival processes and a versatile model for wireless channel capacity, and derive a set of results for various performance measures, including delay, backlog, and delayconstrained capacity. To demonstrate the use of the theory, we focus on dependence manipulation in wireless channel capacity, where we use copula to represent the dependence structure of the underlying Markov process of wireless channel capacity. We show that, based on a priori information of the temporal dependence of the uncontrollable parameters and the spatial dependence between the uncontrollable and controllable parameters, we can construct a sequence of temporal copulas of the Markov process and obtain a sequence of transition matrices of the controllable parameters to achieve the demanded dependence properties of the wireless channel capacity. This dependence manipulation technique is validated by simulation.

format_quoteDependence manipulation techniques achieved desired wireless channel capacity properties through copulas, demonstrating effective control of stochastic parameters.format_quote

CoShare: An Efficient Approach for Redundancy Allocation in NFV

IEEE ACM Transactions on Networking, Jun 1, 2022

An appealing feature of Network Function Virtualization (NFV) is that in an NFV-based network, a ... more An appealing feature of Network Function Virtualization (NFV) is that in an NFV-based network, a network function (NF) instance may be placed at any node. On the one hand this offers great flexibility in allocation of redundant instances, but on the other hand it makes the allocation a unique and difficult challenge. One particular concern is that there is inherent correlation among nodes due to the structure of the network, thus requiring special care in this allocation. To this aim, our novel approach, called CoShare, is proposed. Firstly, its design takes into consideration the effect of network structural dependency, which might result in the unavailability of nodes of a network after failure of a node. Secondly, to efficiently make use of resources, CoShare proposes the idea of shared reservation, where multiple flows may be allowed to share the same reserved backup capacity at an NF instance. Furthermore, CoShare factors in the heterogeneity in nodes, NF instances and availability requirements of flows in the design. The results from a number of experiments conducted using realistic network topologies show that the integration of structural dependency allows meeting availability requirements for more flows compared to a baseline approach. Specifically, CoShare is able to meet diverse availability requirements in a resource-efficient manner, requiring, e.g., up to 85% in some studied cases, less resource overbuild than the baseline approach that uses the idea of dedicated reservation commonly adopted for redundancy allocation in NFV.

format_quoteCoShare reduces resource overbuild by up to 85% compared to traditional dedicated reservation methods for redundancy in NFV networks.format_quote

Some Properties of Length Rate Quotient Shapers

arXiv (Cornell University), Jul 11, 2021

Length Rate Quotient (LRQ) is the first algorithm of interleaved shaping -a novel concept propose... more Length Rate Quotient (LRQ) is the first algorithm of interleaved shaping -a novel concept proposed to provide per-flow shaping for a flow aggregate without per-flow queuing. This concept has been adopted by Time-Sensitive Networking (TSN) and Deterministic Networking (DetNet). An appealing property of interleaved shaping is that, when an interleaved shaper is appended to a FIFO system, it does not increase the worst-case delay of the system. Based on this "shaping-for-free" property, an approach has been introduced to deliver bounded end-to-end latency. Specifically, at each output link of a node, class-based aggregate scheduling is used together with one interleaved shaper per-input link and per-class, and the interleaved shaper re-shapes every flow to its initial traffic constraint. In this paper, we investigate other properties of interleaved LRQ shapers, particularly as stand-alone elements. In addition, under per-flow setting, we also investigate per-flow LRQ based flow aggregation and derive its properties. The analysis focuses directly on the timing of operations, such as shaping and scheduling, in the network. This timing based method can be found in the Guaranteed Rate (GR) server model and more generally the max-plus branch of network calculus. With the derived properties, we not only show that an improved end-to-end latency bound can be obtained for the current approach, but also demonstrate with two examples that new approaches may be devised. End-to-end delay bounds for the three approaches are derived and compared. As a highlight, the two new approaches do not require different node architectures in allocating (shaping / scheduling) queues, which implies that they can be readily adapted for use in TSN and DetNet. This together with the derived properties of LRQ shed new insights on providing the TSN / DetNet qualities of service.

format_quoteNew approaches to achieve improved end-to-end latency bounds were demonstrated, adaptable without architecture changes for TSN and DetNet, enhancing existing models.format_quote