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Author

Jibo Wei

Other affiliations: University of Oulu
Bio: Jibo Wei is an academic researcher from National University of Defense Technology. The author has contributed to research in topics: Synchronization & Wireless network. The author has an hindex of 7, co-authored 19 publications receiving 133 citations. Previous affiliations of Jibo Wei include University of Oulu.

Papers
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Proceedings ArticleDOI
23 Oct 2006
TL;DR: In-depth simulation shows that AMARE yields significantly higher throughput than other existing schemes including auto rate fallback (ARF) scheme and its variants, in various running conditions.
Abstract: An Adaptive Multirate Auto Rate Fallback (AMARF) protocol is proposed for IEEE 802.11 WLANs. The key idea is to assign each data rate a unique success threshold, which is a criterion to switch one rate to the next higher rate, and the success thresholds can be changed dynamically in an adaptive manner according to the running conditions, such as packet length and channel parameters. Moreover, the proposed protocol can be implemented without any change to the current IEEE 802.11 standards. Our in-depth simulation shows that AMARF yields significantly higher throughput than other existing schemes including Auto Rate Fallback (ARF) scheme and its variants, in various running conditions.

33 citations

Journal ArticleDOI
TL;DR: This letter proposes a new approach to model the intra-flow contention problem in multi-hop networks that takes into consideration of neighboring interference, hidden-node collision and multi-rate scenario.
Abstract: This letter proposes a new approach to model the intra-flow contention problem in multi-hop networks. The model takes into consideration of neighboring interference, hidden-node collision and multi-rate scenario. It can be easily used to do admission control or to calculate the end-to-end capacity of a given multi-hop route. Simulation results validate its accuracy.

24 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated the mean square error (MSE) performance of machine learning-based channel estimation in orthogonal frequency division multiplexing (OFDM) systems and derived a clear analytical relation between the size of the training data and performance.
Abstract: Recently, machine learning-based channel estimation has attracted much attention. The performance of machine learning-based estimation has been validated by simulation experiments. However, little attention has been paid to the theoretical performance analysis. In this paper, we investigate the mean square error (MSE) performance of machine learning-based estimation. Hypothesis testing is employed to analyze its MSE upper bound. Furthermore, we build a statistical model for hypothesis testing, which holds when the linear learning module with a low input dimension is used in machine learning-based channel estimation, and derive a clear analytical relation between the size of the training data and performance. Then, we simulate the machine learning-based channel estimation in orthogonal frequency division multiplexing (OFDM) systems to verify our analysis results. Finally, the design considerations for the situation where only limited training data is available are discussed. In this situation, our analysis results can be applied to assess the performance and support the design of machine learning-based channel estimation.

17 citations

Proceedings ArticleDOI
29 Nov 2012
TL;DR: This paper considers a multi-cell relay aided orthogonal frequency division multiple access (OFDMA) downlink system, in which all stations are coordinated by a central controller for resource allocation (RA), and an iterative RA algorithm is proposed to optimize mode selection, subcarrier assignment and power allocation alternatively.
Abstract: This paper considers a multi-cell relay aided orthogonal frequency division multiple access (OFDMA) downlink system, in which all stations are coordinated by a central controller for resource allocation (RA). The decode-and-forward (DF) protocol with selection relaying (SR) is applied. The problem considered is the maximization of the weighted sum of per cell min-rate (WSMR) with a total power constraint in each cell. An iterative RA algorithm is proposed to optimize mode selection (decision whether the relay should help or not), subcarrier assignment (MSSA) and power allocation (PA) alternatively. Each iteration is composed of the MSSA stage and the PA stage. During the MSSA stage, instead of the original objective function, a lower bound is maximized leading to lower complexity. The lower complexity problem is decoupled into mixed integer linear programs (MILP) that can easily be solved by typical MILP solvers. During the PA stage, an algorithm based on single condensation and geometric programming PA (SC-GPPA) is designed to optimize PA with the tentative MSSA results. The convergence of the proposed RA algorithm is proven. Finally, the performance of the RA algorithm and the benefit of using SR are illustrated through numerical experiments.

11 citations

Proceedings ArticleDOI
26 Jun 2006
TL;DR: An improved contention-free fragmentation burst (CFF) scheme, by which the source immediately retransmits the failed fragment without backoff procedure except for the first one, and a channel adaptive fragmentation (ADF) scheme based on CFF is proposed to combat both channel errors and collisions.
Abstract: We first examine the impact of channel errors and collisions on the performance of legacy IEEE 802.11 fragmentation, and find the optimal fragment size depends on both channel condition and network size. Then, we present an improved contention-free fragmentation burst (CFF) scheme, by which the source immediately retransmits the failed fragment without backoff procedure except for the first one. Finally, a channel adaptive fragmentation (ADF) scheme based on CFF is proposed to combat both channel errors and collisions. ADF can distinguish frame transmission failure caused by collision from that by channel error in moderate noisy channel. Simulations show our CFF and ADF have distinct performance improvements in noisy channel and large size networks.

10 citations


Cited by
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Journal ArticleDOI
TL;DR: An up-to-date review of wireless communications service provisioning from High-Altitude Platforms (HAPs) in rural or remote areas exploiting cellular radio spectrum and a comprehensive review of significant HAP related studies is presented.

70 citations

Journal ArticleDOI
TL;DR: This paper proposes two new RA techniques for industrial communication systems that are typically subjected to tight reliability and timing requirements and evaluates their behavior by means of numerical simulations carried out for typical industrial traffic profiles, encouraging since the proposed RA techniques show in most cases better performance than ARF.
Abstract: The performance of the IEEE 802.11 WLAN are influenced by the wireless channel characteristics that reflect on the signal-to-noise ratio (SNR), particularly in industrial communication systems, that often operate in harsh environments. In order to cope with SNR reductions, the IEEE 802.11 WLAN specification suggests to adapt (reduce) the transmission rate, since the modulation techniques employed at the lower rates are more robust. However, the standard does not define any rate adaptation (RA) technique, leaving the actual implementation to the device manufacturers choice. In this paper we focus on RA techniques for industrial communication systems that are typically subjected to tight reliability and timing requirements. In detail, we compare the performance figures of a general purpose widespread technique, namely the automatic rate fallback (ARF), with those of the RA techniques actually implemented on two commercially available IEEE 802.11 devices via a set of practical experiments. The obtained results show that these techniques are characterized by a relevant number of packet retransmissions that may introduce a considerable randomness on the service time, possibly leading to performance degradation. Consequently, we propose two new techniques and evaluate their behavior by means of numerical simulations carried out for typical industrial traffic profiles. The outcomes are encouraging since the proposed RA techniques show in most cases better performance than ARF.

62 citations

Journal ArticleDOI
21 May 2019
TL;DR: This paper presents several major solutions that tackled this issue to achieve real-time and reliability guarantees in wireless networked control systems, capitalizing on the strong efforts devoted to the adoption of IEEE 802.11 physical layer (PHY) technologies.
Abstract: The adoption of real-time wireless technologies within the ever-growing field of networked industrial control systems is continuously gaining popularity. Widespread sensing and actuation devices based on high-throughput wireless standards allow for an increased system mobility and lower configuration and maintenance costs. The IEEE 802.11 standard, especially in its most recent amendments, pushes performance to a very high level, theoretically approaching those of the most common real-time Ethernet networks. Its nondeterministic communication behavior, however, makes 802.11 unsuitable for mission- and safety-critical applications with high-reliability requirements, at least in its standard form. In this paper, we present several major solutions that tackled this issue to achieve real-time and reliability guarantees in wireless networked control systems, capitalizing on the strong efforts devoted to the adoption of IEEE 802.11 physical layer (PHY) technologies. We first provide a deep analysis of the 802.11 protocols in order to propose guidelines toward smart parameter selection at the data-link layer (DLL). In addition, the design of effective rate selection algorithms is considered as a way of increasing both the timeliness and reliability of data delivery. A further systematic solution is represented by real-time (RT)-WiFi, a new time-division multiple-access (TDMA)-based highly configurable DLL protocol that enables high-speed hard real-time data exchange over 802.11 networks. An important goal of this paper is also to provide a thorough comparison among different discussed solutions, in order to put in evidence their advantages and disadvantages, possibly in relation with systems based on different underlying PHYs. We will finally highlight the open challenges and future directions in this active research field.

58 citations

Journal ArticleDOI
TL;DR: The goal is to discuss the fundamental concepts and relevant features of different radio resource management criteria, including water-filling, max–min fairness, proportional fairness, cross-layer optimization, utility maximization, and game theory, also including a toy example with two terminals to compare the performance of the different schemes.

50 citations

Journal ArticleDOI
TL;DR: This paper addresses a weighted sum rate (WSR) maximization problem for downlink OFDMA aided by a decode-and-forward (DF) relay under a total power constraint by proposing a novel subcarrier-pair based opportunistic DF relaying protocol.
Abstract: This paper addresses a weighted sum rate (WSR) maximization problem for downlink OFDMA aided by a decode-and-forward (DF) relay under a total power constraint. A novel subcarrier-pair based opportunistic DF relaying protocol is proposed. Specifically, user message bits are transmitted in two time slots. A subcarrier in the first slot can be paired with a subcarrier in the second slot for the DF relay-aided transmission to a user. In particular, the source and the relay can transmit simultaneously to implement beamforming at the subcarrier in the second slot. Each unpaired subcarrier in either the first or second slot is used for the source's direct transmission to a user. A benchmark protocol, same as the proposed one except that the transmit beamforming is not used for the relay-aided transmission, is also considered. For each protocol, a polynomial-complexity algorithm is developed to find at least an approximately optimum resource allocation (RA), by using continuous relaxation, the dual method, and Hungarian algorithm. Instrumental to the algorithm design is an elegant definition of optimization variables, motivated by the idea of regarding the unpaired subcarriers as virtual subcarrier pairs in the direct transmission mode. The effectiveness of the RA algorithm and the impact of relay position and total power on the protocols' performance are illustrated by numerical experiments. It is shown that for each protocol, it is more likely to pair subcarriers for relay-aided transmission when the total power is low and the relay lies in the middle between the source and user region. The proposed protocol always leads to a maximum WSR equal to or greater than that for the benchmark one, and the performance gain of using the proposed one is significant especially when the relay is in close proximity to the source and the total power is low. Theoretical analysis is presented to interpret these observations.

42 citations