Probability Of Reception Research Articles

An Experimental Evaluation of the Reliability of LoRa Long-Range Low-Power Wireless Communication

Recent technological innovations allow compact radios to transmit over long distances with minimal energy consumption and could drastically affect the way Internet of Things (IoT) technologies communicate in the near future. By extending the communication range of links, it is indeed possible to reduce the network diameter to a point that each node can communicate with almost every other node in the network directly. This drastically simplifies communication, removing the need of routing, and significantly reduces the overhead of data collection. Long-range low-power wireless technology, however, is still at its infancy, and it is yet unclear (i) whether it is sufficiently reliable to complement existing short-range and cellular technologies and (ii) which radio settings can sustain a high delivery rate while maximizing energy-efficiency. To shed light on this matter, this paper presents an extensive experimental study of the reliability of LoRa , one of the most promising long-range low-power wireless technologies to date. We focus our evaluation on the impact of physical layer settings on the effective data rate and energy efficiency of communications. Our results show that it is often not worth tuning parameters, thereby reducing the data rate in order to maximize the probability of successful reception, especially on links at the edge of their communication range. Furthermore, we study the impact of environmental factors on the performance of LoRa, and show that higher temperatures significantly decrease the received signal strength and may drastically affect packet reception.

Non-Orthogonal Multiple Access for High-Reliable and Low-Latency V2X Communications in 5G Systems

In this paper, we consider a dense vehicular communication network where each vehicle broadcasts its safety information to its neighborhood in each transmission period. Such applications require low latency and high reliability, and thus, we exploit non-orthogonal multiple access to reduce the access latency and to improve the packet reception probability. In the proposed two-fold scheme, the BS performs semi-persistent scheduling and allocates time-frequency resources in a nonorthogonal manner while the vehicles autonomously perform distributed power control with iterative signaling control. We formulate the centralized scheduling and resource allocation problem as equivalent to a multi-dimensional stable roommate matching problem, in which the users and time/frequency resources are considered as disjoint sets of objects to be matched with each other. We then develop a novel rotation matching algorithm, which converges to an L-rotation stable matching after a limited number of iterations. Simulation results show that the proposed scheme outperforms the traditional orthogonal multiple access scheme in terms of the access latency and reliability.

LTE D2D 디스커버리에서 무작위 자원 선택 방법에 대한 성능 분석

LTE D2D는 근접한 단말끼리의 직접적인 정보 교환을 통해 셀룰러 시스템의 데이터 트래픽 부하를 해결하는 핵심 기술이다. 특히 D2D 디스커버리는 LTE D2D를 위한 첫 단계로서 단말이 각자의 상태 정보를 주변 단말에게 브로드캐스트 하여 자신을 알리는 과정이다. 디스커버리 메시지 전송의 안정성을 평가하기 위해 시뮬레이션 기반의 성능 평가가 수행되었지만, 한정적인 상황에서 이루어진 경우가 많아 본 논문에서는 일반적인 환경에서 이를 평가할 수 있는 수학적 분석을 제안한다. 제안하는 분석은 확률 기하 이론을 바탕으로 수행되며, 자원 충돌과 인밴드 방사에 의한 간섭의 효과를 모두 고려한다. 우리는 디스커버리 메시지의 수신 성공 확률을 송수신 단말 간의 거리의 함수로 유도하고, 시뮬레이션 결과를 통해 제안하는 분석의 정확도를 확인한다. Long Term Evolution device-to-device (LTE D2D) is a key technology to mitigate data traffic load in a cellular system. It facilitates direct data exchange between neighboring users, which is preceded by D2D discovery. Each device advertises its presence to neighboring devices by broadcasting its discovery message. In this paper, we develop a mathematical analysis to assess the probability that discovery messages are successfully transmitted at the D2D discovery stage. We make use of stochastic geometry for modeling spatial statistics of nodes in a two dimensional space. It reflects signal to noise plus interference ratio (SINR) degradation due to resource collision and in-band emission, which leads to the discovery message reception probability being modeled as a function of the distance between the transmitter and the receiver. Numerical results verify that the newly developed analysis accurately estimates discovery message reception probabilities of nodes at the D2D discovery stage.

Delay on Broadcast Erasure Channels Under Random Linear Combinations

We consider a transmitter broadcasting random linear combinations (over a field of size $d$) formed from a block of $c$ packets to a collection of $n$ receivers, where the channels between the transmitter and each receiver are independent erasure channels with reception probabilities $\mathbf{q} = (q_1,\ldots,q_n)$. We establish several properties of the random delay until all $n$ receivers have recovered all $c$ packets, denoted $Y_{n:n}^{(c)}$. First, we provide lower and upper bounds, exact expressions, and a recurrence for the moments of $Y_{n:n}^{(c)}$. Second, we study the delay per packet $Y_{n:n}^{(c)}/c$ as a function of $c$, including the asymptotic delay (as $c \to \infty$), and monotonicity (in $c$) properties of the delay per packet. Third, we employ extreme value theory to investigate $Y_{n:n}^{(c)}$ as a function of $n$ (as $n \to \infty$). Several results are new, some results are extensions of existing results, and some results are proofs of known results using new (probabilistic) proof techniques.

Energy-Efficient Broadcasting Scheme for Smart Industrial Wireless Sensor Networks

In smart Industrial Wireless Sensor Networks (IWSNs), sensor nodes usually adopt a programmable technology. These smart devices can obtain new or special functions by reprogramming: they upgrade their soft systems through receiving new version of program codes. If sensor nodes need to be upgraded, the sink node will propagate program code packets to them through “one-to-many” broadcasting, and therefore new capabilities can be obtained, forming the so-called Software Defined Network (SDN). However, due to the high volume of code packet, the constraint energy of sensor node, and the unreliable link quality of wireless network, rapidly broadcasting the code packets to all nodes in network can be a challenge issue. In this paper, a novel Energy-efficient Broadcast scheme with adjustable broadcasting radius is proposed aiming to improve the performance of network upgrade. In our scheme, the nonhotspots sensor nodes take full advantage of their residual energy caused in data collection period to improve the packet reception probability and reduce the broadcasting delay of code packet transmission by enlarging the broadcasting radius, that is, the transmitting power. The theoretical analyses and experimental results show that, compared with previous work, our approach can averagely reduce the Network Upgrade Delay (NUD) by 14.8%–45.2% and simultaneously increase the reliability without harming the lifetime of network.

Successful Packet Reception Analysis in Multi-Packet Reception Wireless Systems

In this letter, we analyze the individual probability of receiving a packet when $n$ nodes transmit simultaneously to a single receiver and a multi-packet reception (MPR) scheme is adopted at the physical layer. The main contribution of this letter is the characterization of the average number of packets successfully received. The generic methodology proposed to compute the probability of successful reception of a packet is obtained taking into account the stochastic nature of the path loss due to the spatial distribution of the nodes, as well as shadowing and fast fading effects. The accuracy of the theoretical approach is finally assessed through simulations, showing that for a generic MPR system, there is an optimal number of transmitters that maximize the average number of received packets.

Diversity Backpressure Scheduling and Routing With Mutual Information Accumulation in Wireless Ad-Hoc Networks

We suggest and analyze algorithms for routing in multi-hop wireless ad-hoc networks that exploit mutual information accumulation as the physical layer transmission scheme, and are capable of routing multiple packet streams (commodities) when only the average channel state information is present and that only locally. The proposed algorithms are modifications of the Diversity Backpressure (DIVBAR) algorithm, under which the packet whose commodity has the largest "backpressure metric" is chosen to be transmitted and is forwarded through the link with the largest differential backlog (queue length). In contrast to traditional DIVBAR, each receiving node stores and accumulates the partially received packet in a separate "partial packet queue", thus increasing the probability of successful reception during a later possible retransmission. We present two variants of the algorithm: DIVBAR-RMIA, under which all the receiving nodes clear the received partial information of a packet once one or more receiving nodes firstly decode the packet; and DIVBAR-MIA, under which all the receiving nodes retain the partial information of a packet until the packet has reached its destination. We characterize the network capacity region with RMIA and prove that (under certain mild conditions) it is strictly larger than the network capacity region with the repetition (REP) transmission scheme that is used by the traditional DIVBAR. We also prove that DIVBAR-RMIA is throughput-optimum among the polices with RMIA, i.e., it achieves the network capacity region with RMIA, which in turn demonstrates that DIVBAR-RMIA outperforms traditional DIVBAR on the achievable throughput. Moreover, we prove that DIVBAR-MIA performs at least as well as DIVBAR-RMIA with respect to throughput. Simulations also confirm these results.

Equal Gain Combining in Poisson Networks With Spatially Correlated Interference Signals

We study the successful reception probability and the area spectral efficiency (ASE) of equal gain receivers in a network where transmitters are distributed according to a Poisson point process. Considering spatially correlated interference signals, we derive exact analytical expression of the successful reception probability for two receive antennas and tight approximations for more than two receive antennas. Also, we give an approximation for the optimal transmitter density maximizing the ASE. The results show that the fully-correlated case where interference on different antennas are from the same set of transmitters gives pessimistic successful reception probability, while the uncorrelated case is optimistic.

CubeSat constellation design for air traffic monitoring

Suitably equipped global and local air traffic can be tracked. The tracking information may then be used for control from ground-based stations by receiving the Automatic Dependent Surveillance-Broadcast (ADS-B) signal. In this paper, we describe a tool for designing a constellation of small satellites which demonstrates, through high-fidelity modeling based on simulated air traffic data, the value of space-based ADS-B monitoring. It thereby provides recommendations for cost-efficient deployment of a constellation of small satellites to increase safety and situational awareness in the currently poorly-served surveillance area of Alaska. Air traffic data were obtained from NASA's Future ATM Concepts Evaluation Tool, for the Alaskan airspace over one day. The results presented were driven by MATLAB and the satellites propagated and coverage calculated using AGI's Satellite Tool. While Ad-hoc and precession spread constellations have been quantitatively evaluated, Walker constellations show the best performance in simulation. Sixteen satellites in two perpendicular orbital planes are shown to provide more than 99% coverage over representative Alaskan airspace and the maximum time gap where any airplane in Alaska is not covered is six minutes, therefore meeting the standard set by the International Civil Aviation Organization to monitor every airplane at least once every fifteen minutes. In spite of the risk of signal collision when multiple packets arrive at the satellite receiver, the proposed constellation shows 99% cumulative probability of reception within four minutes when the airplanes are transmitting every minute, and at ~100% reception probability if transmitting every second. Data downlink can be performed using any of the three ground stations of NASA Earth Network in Alaska.

Kalman Filtering With Relays Over Wireless Fading Channels

This note studies the use of relays to improve the performance of Kalman filtering over packet dropping links. Packet reception probabilities are governed by time-varying fading channel gains, and the sensor and relay transmit powers. We consider situations with multiple sensors and relays, where each relay can either forward one of the sensors' measurements to the gateway/fusion center, or perform a simple linear network coding operation on some of the sensor measurements. Using an expected error covariance performance measure, we consider optimal and suboptimal methods for finding the best relay configuration, and power control problems for optimizing the Kalman filter performance. Our methods show that significant performance gains can be obtained through the use of relays, network coding and power control, with at least 30-40% less power consumption for a given expected error covariance specification.

Transmission power allocation of NCSs with Markov channel assignment

This paper investigates networked control systems (NCSs) where the sensors communicate with the remote controller via a wireless fading channel. Each time the channel can accommodate just one sensor for communication and the access to the channel of the sensors is driven by a random event. When a sensor is triggered to send its measurement, it can choose to use a high power or a low power to save energy. The power level of the sensor determines the probability of successful packet reception at the controller. This paper aims to find an appropriate transmission power allocation method for the sensors jointly with a system controller so that the NCS is stabilized with a given energy budget. By introducing a Markov chain model for the medium-access constraint and modeling the packet dropout as a Bernoulli process, we derive a new model and stability conditions for the NCSs, which are given in terms of the transition probabilities of the Markov chain and different packet reception rates. An interesting power scheduling policy is obtained and two kinds of controller design schemes are given depending on whether the medium-access status of the sensors is acknowledged to the controller or not. The results are then extended to the case of large-scale systems and an optimal co-design methodology which can stabilize the whole set of systems with largest stability margin is proposed. The effectiveness of the presented method is demonstrated by numerical simulations.

To send or to defer? Improving the IEEE 802.11p/1609.4 transmission scheme

The IEEE 1609.4 protocol has been proposed to improve message delivery in Vehicular Ad Hoc Networks (VANETs) through its multi-channel usage. To ensure good performance for safety applications, during the first half of a synchronization interval, each vehicle tunes a dedicated Control CHannel (CCH) to exchange safety messages, and during the second half, either it stays on the CCH or switches to one of the six available Service CHannels (SCH). As demonstrated in the literature, such behavior leads safety messages to suffer from synchronous collisions at the start of the CCH interval, as well as from high end-to-end delays caused by the queue-up during the SCH intervals. To address these issues, we propose DMS, a Distributed MAC Scheduler that relies on the Optimal Stopping Theory to evenly balance the channel load by introducing tolerated deferring delays before sending a message. This ensures a higher reception probability and lower collision risks, while complying with Enhanced Distributed Channel Access (EDCA) access categories (ACs). Simulation study shows the ability of our approach to increase the reception rate of safety messages up to 25%, to decrease loses up to 47%, and to improve the load balancing during the CCH interval.

Historical Spectrum Sensing Data Mining for Cognitive Radio Enabled Vehicular Ad-Hoc Networks

In vehicular ad-hoc network (VANET), the reliability of communication is associated with driving safety. However, research shows that the safety-message transmission in VANET may be congested under some urgent communication cases. More spectrum resource is an effective way to solve transmission congestion. Hence, we introduce cognitive radio (CR) enabled VANET (CR-VANET), where CR device can detect possible idle spectrum for VANET communications and assist to timely broadcast safety-message. Given high-speed mobility of vehicles and dynamically-changing availability of channels, a novel prediction algorithm is proposed to pick out the channel with the greatest probability of availability, which can meet the quality of service (QoS) requirement of urgent communications and effectively avoid conflict with licensed users. Specifically, the spatiotemporal correlations among historical spectrum sensing data are exploited to form prior knowledge of channel availability probability, and Bayesian inference is used to derive posterior probability of channel availability. Comparing with other spectrum detection methods, the proposed algorithm has more than 8 percent detection performance improvement at false alarm probability 0.2, and thus can avoid access conflict with licensed users dramatically. Furthermore, the proposed algorithm always has larger packet reception probability (PRP) and lower transmission delay compared with conventional VANET broadcasting. Hence, the proposed algorithm can improve reliability of safety-message transmission and enhance driving safety significantly.

On Network Topology Reconfiguration for Remote State Estimation

In this paper, we investigate network topology reconfiguration in wireless sensor networks for remote state estimation, where sensor observations are transmitted, possibly via intermediate sensors, to a central gateway/estimator. The time-varying wireless network environment is modelled by the notion of a network state process, which is a randomly time-varying semi- Markov chain and determines the packet reception probabilities of links at different times. For each network state, different network configurations can be used, which govern the network topology and routing of packets. The problem addressed is to determine the optimal network configuration to use in each network state, in order to minimize an expected error covariance measure. Computation of the expected error covariance cost function has a complexity of O(2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MΔmax</sup> ), where M is the number of sensors and Δ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> is the maximum time between transitions of the semi- Markov chain. A sub-optimal method which minimizes the upper bound of the expected error covariance, that can be computed with a reduced complexity of O(2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</sup> ), is proposed, which in many cases gives identical results to the optimal method. Conditions for estimator stability under both the optimal and suboptimal reconfiguration methods are derived using stochastic Lyapunov functions. Numerical results and comparisons with other low complexity approaches demonstrate the performance benefits of our approach.

Link Quality Prediction for 802.11 MANETs in Urban Microcells

In this paper we derive the optimal link quality predictor (LQPR) whose parameters are estimated from signal power and node speed samples. We propose a fast estimator for these parameters whose computational complexity is three orders lower than that of the optimal estimator with only a slight loss in accuracy thus enabling real- time execution. We show that using the most recent local mean of the signal as a predictor of future signal strength is also a very close approximation to the optimal predictor. This is the central result of this paper. It obviates the need for complex and/or computationally intensive link quality predictors for 802.11 in urban microcells and has the advantage of not requiring node speed information. The LQPRs are evaluated against the lower error bound. We show that the LQPR based on the most recent local mean of the signal predicts the packet reception probability for pedestrians in urban microcells on average with a mean absolute error of 13.47%, 16.54%, 18.21% and 19.38% for 1 s, 2 s, 3 s and 4 s into the future respectively. This LQP accuracy resembles closely the lower error bound with, for example, a difference of only 2.47% at 2 s into the future.

Reliability and performance of general two-dimensional broadcast wireless network

In this paper, an analytic model is built to study the medium access control (MAC) performance and reliability of general two-dimensional (2-D) IEEE 802.11 based wireless networks for one-hop broadcast communications. First, a semi-Markov process (SMP) model is introduced to capture the medium contention and backoff behavior and the impact of hidden terminal problem in IEEE 802.11 broadcast wireless networks in a more precise way. An M/G/1/K queue is used to model arrival and service of messages in an individual mobile terminal. To the contention for the shared medium, the SMP model interacts with the M/G/1/K queue through fixed-point iteration. Furthermore, based on the fixed-point solution, performance metrics including packet delivery probability (PDP), MAC-level and Application-level transmission delay, and MAC-level and Application-level packet reception ratio (PRR) are derived. The 2-D PDPs are derived through a coverage area computation for the impact of hidden terminal problem and concurrent transmissions to evaluate point-to-point reception probability, and then through integration of the reception probabilities over the circular intended range of the sending node. The analytical model takes into account IEEE 802.11 backoff counter process, hidden terminal problem, message inter-arrival interval, distinct transmission range, carrier sensing and interference ranges, and Nakagami fading channel with distance dependent path loss. Finally, as an example, the proposed analytic model is applied to a 2-D ad hoc network. The new model is validated through extensive simulations and new observations about the effects of network parameters on the performance and reliability are obtained.

Efficient Broadcasting in VANETs Using Dynamic Backbone and Network Coding

Multihop data dissemination in vehicular ad hoc networks (VANETs) is very important for the realization of collision avoidance systems and many other interesting applications. However, designing an efficient data dissemination protocol for VANETs has been a challenging issue due to vehicle movements, limited wireless resources, and the lossy characteristics of wireless communication. In this paper, we propose a protocol that can provide a lightweight and reliable solution for data dissemination in VANETs. The protocol employs dynamically generated backbone vehicles to disseminate broadcast packets to reduce the MAC-layer contention time at each node while maintaining a high packet dissemination ratio by taking into account vehicle movement dynamics and the link quality between vehicles for the backbone selection. The protocol also uses network coding to reduce the protocol overhead and to improve the packet reception probability as compared with conventional approaches. We use theoretical analysis and computer simulations to show the advantage of the proposed protocol over other existing alternatives.

Modeling of propagation of road hazard information in sparse vehicular ad hoc networks

In this paper, we study the propagation of road hazard information to vehicles which enter the hazard segment of a highway in a sparse 1D vehicular ad hoc network (VANET) with store-and-forward mechanism. Store-and-forward is an option for message propagation in sparse vehicular networks where connectivity is intermittent. Upon receiving the message, the vehicle becomes an informed vehicle, it carries the message for a while and then forwards it to the approaching vehicles which are about to enter the highway segment. In this way, a platoon of informed vehicles is formed. We establish an analytical model to obtain the probability that a vehicle receives the message and joins the informed platoon. Moreover, we prove that traffic dynamics increase the reception probability of messages. We find the expected message propagation delay in the platoon using the store-and-forward policy. We also show that the propagation delay in store-and-forward inter-vehicle communications is tightly related to traffic parameters such as traffic flow rate and vehicle speeds on the highway. Results show that for smaller transmission ranges, smaller platoons are formed, the expected message propagation delay in the platoon is low, and it increases very slightly as the traffic flow rate increases. But for larger transmission ranges, larger platoons are formed, the expected delay is high, and it increases remarkably with a small increase in the traffic flow rate. The impacts of some network and traffic parameters such as transmission range, speed of vehicles, and highway speed limits on the message propagation are investigated as well. Finally, the accuracy of the analytical results is evaluated by an extensive simulation study.

Reliable and Swift Message Broadcast Method in Vehicular Ad Hoc Networks

A vehicular ad hoc network (VANET) could deliver safety-related messages reliably within a short time to increase road safety. Since safety-related messages should be sent to a set of unspecified receivers, they are delivered by broadcast method. However, the broadcast method specified in the IEEE 802.11p does not have a collision avoidance procedure and receivers do not acknowledge when they receive a broadcast frame. In addition, frames could be lost and corrupted. Therefore, as the portion of nodes that do not receive a broadcast frame increases, the effectiveness of a safety application decreases. To tackle the problem, we propose a reliable and swift message broadcast method (RSMB). In RSMB, to expedite message dissemination process, a relay node is selected in a distributed manner considering the progress made to a frame and the delay requirements of an application. In addition, a relay node broadcasts a message multiple times to assure that the probability that the other nodes successfully receive the message at least once is larger than a given threshold value. Since the number of rebroadcasts is regulated based on the successful message reception probability, the additional bandwidth needed to increase the reliability of broadcast is reasonably small.

Communication- and position-aware reconfigurable route optimization in large-scale mobile sensor networks

We consider the problem of route selection and optimization for a mobile sensor network, which involves two nodes transferring information over a large area using a number of intermediate routers in the presence of noise, path loss, multipath fading, and interference. The communication- and position-aware reconfigurable (COMPARE) route optimization framework is proposed to improve the end-to-end throughput of the routes in the realistic communication environment. Initially, a communication-aware route selection strategy selects the optimal route by integrating the routing decisions with the link quality. The quality of the wireless link is characterized by the reception probability, i.e., the probability of successfully receiving packets over a realistic communication link. The selected route is reconfigured by exploiting the multipath fading, position information, and the mobility of the nodes during the phase of position-aware optimization. The optimal position for a router is heuristically found using a priori information about fading channels and the positions of transmitting and interfering nodes. The router is guided to the optimal position using the feedback mobility control, and only the route selected by the COMPARE framework is used for data transmission between the source and destination node. We illustrate through simulations that the proposed framework provides routes with considerably better performance than conventional route selection metrics, in terms of the end-to-end throughput.