Advances in wireless networking, such as 5G, continue to enable the vision of the Internet of Things (IoT), where everything is connected, and much data is collected by IoT devices and made available to interested parties (i.e., application servers). However, events such as botnet attacks (e.g., [1]) demonstrate that there are important challenges in this evolution.In this paper we consider the problem of scalable and secure data publication from IoT devices, with included mechanisms that help towards device attacks prevention and detection. We propose SEDIMENT, a system and methodology which look more specifically at problems that arise in a network with a broad variety of devices, some of which have limited resources and some of which were designed for a less hostile environment. SEDIMENT uses a combination of software root of trust, remote attestation and resource-efficient cryptography, to build a system that scales across heterogeneous computing platforms. It allows for devices that range from battery-powered devices that are intended to operate for long periods up to server-class machines without power constraints. SEDIMENT provides a secure application layer that can be used for common communication paradigms such as publish-subscribe while following zero-trust principles in both protecting the end hosts from the network and other end hosts, as well as protecting the network from the end hosts.

In this article, we propose a novel framework of mobile edge computing (MEC)-based hierarchical machine learning (ML) tasks distribution for the Industrial Internet of Things. It is assumed that a batch of ML tasks, such as anomaly detection, need to be executed timely in an MEC setting, where the devices have limited computing capability while the MEC server (MES) has rich computing resources. Thus, a small ML model for the device and a deep ML model for the MES are pretrained offline using historical data, and then they are deployed accordingly. However, offloading tasks to the MES introduces communications delay. Thus, each device must decide the portion of the tasks to offload to minimize the processing delay. Since the delay and the error of data processing are incurred by communications and ML computing, a joint optimization problem is formulated to minimize the total delay subject to the ML model complexity and inference error rate, data quality, computing capability at the device and MES, and communications bandwidth. A closed-form solution is derived analytically and an optimal offloading strategy selection algorithm is proposed. Insights are provided to understand the tradeoff between communications and ML computing in offloading decisions, and the effects of key parameters in the proposed algorithm are investigated. The numerical results demonstrate the effectiveness of the proposed algorithm.

We consider the problem of relay-assisted transmission for cellular networks. In the considered system, a source node together with n relay nodes are selected in a proportionally fair (PF) manner to transmit to the base station (BS), which uses the maximal ratio combining (MRC) to combine the signals received from the source node in the first half slot and the n relay nodes in the second half slot for successful reception. The proposed algorithm incorporates the PF criterion and cooperative diversity, and is called proportionally fair cooperation (PFC). Compared with the proportional fair scheduling (PFS) algorithm, PFC provides improved efficiency and fairness. The ordinary differential equation (ODE) analysis used to study PFS cannot be used for PFC; otherwise, one has to solve a large number of nonlinear and interrelated ODE equations which is time prohibited. In this paper, we present a mathematical framework for the performance of PFC. The cornerstone of our framework is a realistic yet simple model that captures node cooperation, fading, and fair resource allocation-induced dependencies. We obtain analytical expressions for the throughput gain of PFC over traditional PFS without node cooperation. Compared with the highly time-consuming ordinary differential equation analysis, our formulae are intuitive yet easy to evaluate numerically. To our knowledge, it is the first time that a closed-form expression is obtained for the throughput of relay-assisted transmission in a cellular network with the PF constraint.

This study considers utility-based resource allocation in backbone wireless mesh networks (WMNs). Unlike single-hop cellular networks, a WMN has multi-hop transmissions with multiple contending links, and thus requires more careful design for resource allocation. To this end, we provide a clique-based method with efficient spatial reuse, which is then incorporated into proportionally fair scheduling (PFS) for fair resource management in WMNs. We call it a clique-based proportionally fair scheduling (CBPFS) algorithm. The linear and/or logarithmic rate models used to analyze PFS in single-hop cellular networks cannot be used to analyze CBPFS in backbone WMNs. Using stochastic approximation and recent results on rate modeling for Rayleigh fading channels, we conduct mathematical analysis and obtain a closed-form model to quantify CBPFS performance, without the need of the highly time-consuming ordinary differential equation (ODE) analysis. We use the derived analytical framework to estimate the link throughput of CBPFS and compare it with simulations. It is the first time a closed-form analytical model is developed to quantify the throughput of links in a multi-hop network where links are proportionally fair scheduled.

This paper is concerned with the analysis of proportionally fair scheduling (PFS), and we provide an analytical approximation for the PFS throughput over Rayleigh fading channels. Though quite accurate, the ordinary differential equation (ODE) analysis, typically used to analyze the PFS throughput, is highly time-consuming when there are lots of users. On the other hand, due to the intricate interplay among these ODE equations, the ODE analysis generally fails to provide a closed-form approximation for estimating the PFS throughput unless with simplified models such as the linear rate model to characterize channel capacity. Our aim is to provide a novel framework to evaluate PFS in Rayleigh fading without the above-mentioned limitations. To put our work on a firm base, we use results of stochastic approximation in the analysis and take the Gaussian approximation for capacity modeling for fading channels. Simulations validate this approach and show that our analytic result provides highly accurate estimate of the PFS throughput. Compared to existing studies, our work advances the state of the art in three ways. First, it goes beyond the linear rate model and applies to the commonly used Shannon rate model. Second, it provides accurate estimate of the PFS throughput without the need for the time-consuming ODE analysis. Third, it provides a unified closed-form expression for estimating the PFS throughput for both the linear rate model and the Shannon rate model. It is interesting to note that our analysis provides the same result as existing studies when assuming the linear rate model. More importantly, our formula is intuitive yet easy to evaluate numerically.

In a wireless network, connectivity is arguably the most critical issue that requires significant study since a network can hardly function well if it is disconnected. On the other hand, there are extraordinary interests in exploiting cooperative techniques in wireless networks in recent years. This paper studies the connectivity problem of large cooperative ad hoc networks. Unlike traditional cooperative networks where all nodes are willing to transmit in a collaborative manner, the cooperative network we considered does not assume that all nodes would like to transmit cooperatively when relaying other nodes' traffic. In other words, each node exhibits some sense of selfishness. Specifically, we model nodes in such a way that each node cooperatively transmits with p-selfishness or location-based p-selfishness when relaying other nodes' traffic. For the considered network, we assume that nodes are generated according to a Poisson Point Process (PPP) and techniques based on stochastic geometry and percolation theory are used to analyze the connectivity in such system. To quantify the performance of the cooperative ad hoc network with selfish behavior, we provides an upper bound of node density for such network to maintain connectivity.

In wireline networks, random network coding combined with path diversity provides inherent protection against eavesdropping since the eavesdropper has to compromise nodes along each diverse path, presumably at significant risk and cost per compromise, in order to acquire enough information to decode the source data. This touted ``free security'' does not necessarily apply, however, towireless networks. Since a sophisticated over-the-air eavesdropper at a protected site away from the network can receive transmissions from multiple nodes, without incurring significant additional risk or expense, any inherent protection that network coding provides in this context is unclear. In this paper, we investigate the eavesdropping vulnerability of a mobile ad-hoc network using the current state-of-the-art in random linear network coding and subgraph generation techniques. Specifically, we develop a simulation framework with proper metrics to quantify the eavesdropper's decoding success probability for a network-coded wireless network. Our results, obtained from extensive Monte Carlo simulations, demonstrate that such networks are indeed vulnerable to eavesdropping-and to a remarkable degree. Finally, we experimentally confirm the high degree of eavesdrop vulnerability using packets captured from an operational prototype testbed.

We consider the problem of selective relaying in multi-hop networks. At each slot, a relay and a node along the optimal non-cooperative path are opportunistically selected to transmit to the next-hop node in a cooperative manner. Being a promising scheme for fair resource allocation, the proportional fair scheduling (PFS) algorithm provides excellent balance between throughput and fairness via multi-user diversity and game-theoretic equilibrium. To maximize the overall utility along a cooperative multi-hop path, we apply the proportional fair (PF) criterion in selecting nodes and relays for cooperative transmission. Furthermore, we analyze and provide an analytical expression for end-to-end throughput of an opportunistic relaying, cooperative multi-hop path with proportional fairness constraints over a Rayleigh flat-fading channel. To our knowledge, it is the first time that a closed-form expression is obtained for the throughput of a proportional fair relaying, cooperative multi-hop path. This research is an extension of previous theoretical work on PF for cellular networks.

We consider the problem of fair resource allocation for multi-carrier systems. Opportunistic scheduling exploits the time-varying, location-dependent channel conditions to achieve multi-user diversity. Previous work in this area has focused on the single-user scheduling in single-carrier systems over a narrowband flat-fading channel, where only one node is scheduled at a time. In wideband multi-carrier systems, multiple nodes can be scheduled concurrently over multiple narrowband channels. In this paper, we analyze proportional fair scheduling (PFS) in multi-carrier systems over a wideband frequency-selective channel. In particular, we first derive analytical expressions for the throughput of opportunistic scheduling under proportional fairness constraints in a frequency-selective channel, for both single-user and multi-user systems. Furthermore, we provide closed-form expression to quantify the throughput benefit of the multi-user PFS over the single-user PFS in frequency-selective systems. This research is an extension of our previous theoretical work on opportunistic scheduling over flat-fading channel in narrowband single-carrier systems.

In this paper, we consider a distributed medium access control (MAC) for mobile ad-hoc networks (MANET). We propose an adaptive threshold-based medium contention scheme to exploit diversity gain in multiple dimensions, in particular, the time and user diversity. In our scheme, each node performs a c

RObust Header Compression (ROHC) is a standard specification of a highly robust and efficient header compression scheme. It is specially designed for wireless communication links with large packet error rates and long round trip delay. ROHC is one of the key features in providing Voice over IP (VoIP) service in wireless networks. With ROHC, the headers for each VoIP packet can be much compressed such that VoIP packet can be efficiently transmitted over the air interface with improved capacity. In this paper, we evaluate the performance of ROHC scheme for VoIP application in the lxEV-DO Revision A system. In particular, we examine the compression efficiency and robustness of ROHC algorithm to the packet errors and packet out-of-order over the wireless link. Furthermore, we propose enhancements and configuration recommendations to optimize the ROHC performance for VoIP in lxEV-DO system.

In CDMA 1timesEV-DO Revision A system, an enhanced access channel (EAC) on reverse link with multiple transmission data rates is introduced with improved access performance for the general usage of connection setup. Data Over Signaling (DOS) protocol, also introduced in 1timesEV-DO Rev. A allows an access terminal to send and receive short user data messages over the EAC on reverse link and control channel on forward link DOS is useful for delay sensitive applications such as the call setup messages for push-to-talk and VoIP services. In this paper, we investigate the performance of EAC using both analytical and simulation models. In particular, the delay performance of DOS using the EAC with different data rates and message sizes is analyzed and compared. It is shown that the analytical and simulation results match very well. Furthermore, we propose a method for selecting access channel and traffic channel for transmitting data traffic. The proposed method takes better advantage of DOS for reduced latency and also improves the RF coverage.

While voice-over-Internet protocol (VoIP) on wireline network is maturing, VoIP on wireless mobile network is still in its infancy. This disparity is due to the fact that the wireline bandwidth is abundant and can be traded off for delay performance and overhead, whereas bandwidth in wireless mobile network is still a scarce resource. With the deployment of 1$times$EV-DO revision 0 (DOr0) worldwide, the spectrum efficiency has been significantly improved. However, DOr0 still lacks of features essential for VoIP. For this reason, 1$times$EV-DO revision A (DOrA) has been standardized in the 3GPP2 with many improvements favorable for VoIP implementation. In this paper, we identify challenges and explore the feasibility of implementing VoIP using DOrA. We develop both analytical and simulation models to evaluate the VoIP capacity and delay performance over the air interface.

The radio link control (RLC) for Universal Mobile Telecommunication System (UMTS) is an acknowledgement based transmission protocol. Protocol stalling and deadlock might happen under certain circumstances and thus reduce the system efficiency. In this paper, we propose and investigate three alternative mechanisms with spontaneous retransmissions to prevent protocol stalling. We compare the results indicate that all three methods can prevent protocol stalling quite effectively. In addition, the combined retransmission of the last or the earliest transmitted packet has the best throughput and delay performance and outperforms the other two methods.

UMTS radio link control (RLC) contains a suite of features and options that make it a challenging task for performance evaluation. We develop a periodic-polling-based retransmission model to analyze the RLC protocol. We derive the evolution of the queue length distribution that can be used to construct a Markov chain. While the task of obtaining a closed-form solution for this Markov chain given a general set of system parameters seems to be formidable, we have been able to obtain a closed-form solution for the average system occupancy for some interesting special cases. To validate the efficacy of the analytical model, we perform numerical calculation on the upper and lower bounds of the average packet delay and compare it with the simulation results. The results show that the lower bound derived is very tight.

The radio link control (RLC) protocol in Universal Mobile Telecommunication System (UMTS) contains a suite of features and options which make the protocol very flexible and adaptive to operation in different radio environments and for various applications. We analyze the various features and functions associated with the RLC protocol and evaluate the performance over UMTS specific physical link through simulations. Specifically, we examine the detail behavior of the protocol under various conditions and options, including polling, status transmission mechanism, and packet discard functions. We compare different polling mechanisms and examine their impacts on the delay and throughput as well as acknowledgement overhead. We also compare different discard parameters and service rates and evaluate their impacts on the overall performance. Finally we provide quantitative results for web-browsing traffic which is considered as one of the future applications in 3G wireless networks.

UMTS is a third generation radio access network which supports multimedia-capable mobile communication such as packet data and Internet access. In order to provide end-to-end quality of service (QoS) in the UMTS network, certain features need to be incorporated into the MAC design. One possible way of providing different QoS is via providing priority mechanisms. The priority mechanism can be implemented in terms of access priority, service priority and/or buffer management schemes. In this paper, we three access priority schemes based on the random access channel structure. The three schemes are: random chip delay access (RCDAP), random backoff based access (RBBAP), and variable logical channel based access priority (VLCAP). We discuss scenarios where such access priority schemes may be useful. Via simulations, we evaluated and compared these three access priority schemes, Our results indicate that all three schemes provide delay differentiation. However, only the RBBAP scheme provides delay differentiation among different priority classes over a wide range of access request rates without impacting the throughput of the access requests. The other two schemes may cause the throughput of access requests from the lower priority classes to drop apart from forcing them to have a higher access delay.

We propose and analyze a hybrid automatic repeat request (ARQ) with a selective combining scheme using rate-compatible punctured convolutional (RCPC) codes for fading channels. A finite-state Markov channel model is used to represent the Rayleigh fading channels. We show that the hybrid ARQ with selective combining yields better performance than the generalized type-II ARQ scheme for fading channels. Furthermore, simulation results of real-time video time division multiple access (TDMA) transmission system are given. Better video quality can be obtained by our proposed scheme, with a bounded delay. Analytical results of throughput and packet error rate (PER) are compared to the simulated results. Our analysis based on a finite-state Markov channel model, is shown to give good agreement with simulations.

We form a finite-state Markov channel model to represent Rayleigh fading channels. We develop and analyze a methodology to partition the received signal-to-noise ratio (SNR) into a finite number of states according to the time duration of each state. Each state corresponds to a different channel quality indicated by the bit-error rate (BER). The number of states and SNR partitions are determined by the fading speed of the channel. Computer simulations are performed to verify the accuracy of the model.

We investigate hybrid ARQ schemes for low-bit-rate video transmission over wireless channels. We propose and analyze a hybrid ARQ with a selective combining scheme using rate-compatible punctured convolutional (RCPC) codes on Rayleigh fading channels. It is shown that our scheme performs better than the generalized type-II ARQ for bursty error channels. Simulations of a real-time video TDMA transmission system are also performed. A better video quality can be obtained by our proposed scheme with a bounded delay. Analytical results of the throughput and packet error rate are compared to the simulation results. Our analysis based on a finite-state Markov channel model is shown to give very good agreement with simulations.