Showing papers by "Jiandong Li published in 2011"
TL;DR: Insight is provided into routing protocols designed specifically for large-scale WSNs based on the hierarchical structure and a comparison of each routing protocol is conducted to demonstrate the differences between the protocols.
Abstract: With the advances in micro-electronics, wireless sensor devices have been made much smaller and more integrated, and large-scale wireless sensor networks (WSNs) based the cooperation among the significant amount of nodes have become a hot topic. “Large-scale” means mainly large area or high density of a network. Accordingly the routing protocols must scale well to the network scope extension and node density increases. A sensor node is normally energy-limited and cannot be recharged, and thus its energy consumption has a quite significant effect on the scalability of the protocol. To the best of our knowledge, currently the mainstream methods to solve the energy problem in large-scale WSNs are the hierarchical routing protocols. In a hierarchical routing protocol, all the nodes are divided into several groups with different assignment levels. The nodes within the high level are responsible for data aggregation and management work, and the low level nodes for sensing their surroundings and collecting information. The hierarchical routing protocols are proved to be more energy-efficient than flat ones in which all the nodes play the same role, especially in terms of the data aggregation and the flooding of the control packets. With focus on the hierarchical structure, in this paper we provide an insight into routing protocols designed specifically for large-scale WSNs. According to the different objectives, the protocols are generally classified based on different criteria such as control overhead reduction, energy consumption mitigation and energy balance. In order to gain a comprehensive understanding of each protocol, we highlight their innovative ideas, describe the underlying principles in detail and analyze their advantages and disadvantages. Moreover a comparison of each routing protocol is conducted to demonstrate the differences between the protocols in terms of message complexity, memory requirements, localization, data aggregation, clustering manner and other metrics. Finally some open issues in routing protocol design in large-scale wireless sensor networks and conclusions are proposed.
161 citations
TL;DR: A novel low-delay traffic-adaptive medium access control protocol for wireless body area networks (WBANs) is proposed in the paper that accommodates more devices access to the network and reduces the packet delay obviously without the cost of more energy consumption.
Abstract: IEEE 802.15.4 technology provides one solution for low-rate short range communications. Based on the integrated superframe structure of IEEE 802.15.4, a novel low-delay traffic-adaptive medium access control (LDTA-MAC) protocol for wireless body area networks (WBANs) is proposed in the paper. In LDTA-MAC, the guaranteed time slots (GTSs) are allocated dynamically according to the traffic load. At the same time, the active portion of superframe is kept to be a reasonable duration to decrease the energy consumption of the network devices. Moreover, for the successful GTS requests, the related data packets are transmitted in the current superframe instead of waiting more time to reduce the average packet delay. Simulations are conducted to evaluate the network performance and verify our protocol design. Comparing with IEEE 802.15.4, the results reveal LDTA-MAC accommodates more devices access to the network and reduces the packet delay obviously without the cost of more energy consumption.
46 citations
TL;DR: This letter introduces an observed spectrum sensing issue that: with certain probability, a secondary user (SU) misinterprets a non-interfered primary user (PU) is being interfered, resulting in access opportunity loss.
Abstract: This letter introduces an observed spectrum sensing issue that: with certain probability, a secondary user (SU) misinterprets a non-interfered primary user (PU) is being interfered, resulting in access opportunity loss. This issue termed as spatial false alarm (SFA) problem is one of determinants on SU's medium access probability. However, it is neglected in current research related to spectrum sensing. By thoroughly study, the principle of SFA is presented to reveal the cause of this problem. Moreover, we quantify the impact of SFA by a closed-form expression to correctly evaluate the medium access probability for SU. The simulation results evidence both the importance of SFA and the validity of the derived medium access probability.
23 citations
Patent•
13 Jul 2011
TL;DR: In this paper, a superframe-based efficient media access control method in a wireless body area network, mainly solving the problems that an IEEE (Institute of Electrical and Electronic Engineers) 802.15.4 protocol is incapable of distinguishing service priorities and has time slot waste in a noncompetitive period.
Abstract: The invention discloses a superframe-based efficient media access control method in a wireless body area network, mainly solving the problems that an IEEE (Institute of Electrical and Electronic Engineers) 802.15.4 protocol is incapable of distinguishing service priorities and has time slot waste in a non-competitive period in a wireless body area network. The superframe-based efficient media access control method is realized by adopting the steps of: in a competitive period, setting the competitive period into a high priority service dedicated time slot H, a high priority service spare time slot h and a common time slot by adopting a time slot ALOHA competition mechanism based on the service priority, wherein a common node adopts the three different competition mechanisms according to the quantity of high priority services in the current superframe competitive period; and in a non-competitive period, ensuring that allocation and utilization of a GTS (Guarantee Time Slot) service are carried out by utilizing a micro time slot as a unit and adopting a micro time slot mechanism so as to realize the effective utilization of the time slot. Compared with the IEEE 802.15.4 protocol, thesuperframe-based efficient media access control method disclosed by the invention can not only ensure that the high priority service is transmitted with a higher success probability, but also effectively improve the time slot utilization ratio in the non-competitive period and is suitable for the wireless body area network.
21 citations
TL;DR: Three dynamic sensing strategies are developed that can adaptively schedule the sensing slots/cycles according to the online link conditions without assuming knowledge of the PU traffic model and can improve the efficiency of spectrum utilization while being robust with respect to the uncertainty in thePU traffic pattern.
Abstract: For cognitive radio (CR) networks with user hierarchy, the sensing strategy with "listen-before-talk" (LBT) policy plays a key role in spectrum utilization and primary user (PU) protection. However, existing sensing strategies do not handle satisfactorily the randomness of both user locations and channel conditions in the network environment, resulting in inefficient spectrum utilization. To cope with such randomness, this paper develops three dynamic sensing strategies that can adaptively schedule the sensing slots/cycles according to the online link conditions without assuming knowledge of the PU traffic model. The proposed strategies can improve the efficiency of spectrum utilization while being robust with respect to the uncertainty in the PU traffic pattern. To maximize spectrum utilization, the proposed strategies are formulated through closed-form expressions. Efficient methods are introduced to compute the optimal values of the parameters used in the strategies, such as sensing time and sensing threshold. Simulations verify that the proposed sensing strategies offer an evident improvement on the spectrum utilization of the CR network.
17 citations
01 Dec 2011
TL;DR: A handover trigger time selection strategy based on the prediction of received signal strength that can almost eliminate handover failure and has a good adaptability to the varying network overlapping environment is proposed.
Abstract: Emergence of various radio access networks enables users to communicate with each other anytime and anywhere. Handover management strategy directly influences the user's service continuity performance and quality of service. In this paper, we propose a handover trigger time selection strategy based on the prediction of received signal strength. With auto-regression model, the mobile terminal predicts both the earliest and the latest handover trigger time threshold, and then determines the optimal trigger time. Simulation results show that our proposed method can almost eliminate handover failure and has a good adaptability to the varying network overlapping environment.
15 citations
TL;DR: A group based interference alignment (GIA) scheme is proposed, and it is formulated as an unbounded knapsack problem to obtain group patterns.
Abstract: In the K-user single-input single-output (SISO) frequency-selective fading interference channel, it is shown that the maximal achievable multiplexing gain is almost surely K/2 by using interference alignment (IA). However, when the signaling dimensions are limited, allocating all the resources to all users simultaneously is not optimal. So, a group based interference alignment (GIA) scheme is proposed, and it is formulated as an unbounded knapsack problem. Optimal and greedy search algorithms are proposed to obtain group patterns. Analysis and numerical results show that the GIA scheme can obtain a higher multiplexing gain when the resources are limited.
12 citations
27 Oct 2011
TL;DR: A joint PRB management and power control in LTE self-optimizing networks is proposed using the non-cooperative game with resource consuming pricing into consideration, and the closed-form of optimal PRB andPower control strategies are derived.
Abstract: A joint PRB management and power control in LTE self-optimizing networks is proposed using the non-cooperative game with resource consuming pricing into consideration. We derive the closed-form of optimal PRB and power control strategies, based on which we develop the joint PRB and power control algorithms for the down-link LTE. Simulation results verify the performance of the presented scheme with the benchmark schemes.
6 citations
01 Dec 2011
TL;DR: It is proved that the optimal structure of the source and relay precoders jointly convert the MIMO relay channel into a bank of single-input-single-output (SISO) relay channels without having to assume a beamforming structure to simplify the derivation.
Abstract: We investigate the problem of precoding optimization in an amplify-and-forward (AF) multiple-input-multiple-output (MIMO) relay system. Most reported works on this problem focus chiefly on the design of relay precoder without simultaneously optimizing the direct link. In this paper, we propose a method for joint source/relay precoder design, taking both direct and relay links into account. Our design is based on maximizing the mutual information (MI) under limited transmission power constraints at the source and relay, respectively. We first formulate a constrained optimization problem before relaxing the original cost function for tractability and derive a MI lower bound which asymptotically approaches the exact expression of MI in an iterative fashion. In contrast to previous strategies, we then prove that the optimal structure of the source and relay precoders jointly convert the MIMO relay channel into a bank of single-input-single-output (SISO) relay channels without having to assume a beamforming structure to simplify the derivation. Specifically, the linear precoding design problem degenerates into power loading among multiple SISO relay channels. Applying standard Lagrange technique results in a scalar convex optimization which can be readily solved by iterative water filling. Numerical examples demonstrate that the proposed scheme, either exploiting partial or full channel state information (CSI), significantly outperforms the existing methods.
6 citations
05 Jun 2011
TL;DR: In this article, the average path length of SCR was shown to be O(n O q ) 2 log n O q, where n is the number of cooperative nodes.
Abstract: ≤≤ ⎡⎤ , where M is the number of cooperative nodes. If the average hops between the sender node and its short-cut node is approximately equal to one hope by using the cooperative communication link, the average path length of SCR is () 2 log [] n O q . Compared with other existing
5 citations
15 May 2011
TL;DR: It is formally proved that the path metric is isotonic, which is the necessary and sufficient condition for assuring the proper operation of the routing algorithm.
Abstract: In this paper, we propose a new path metric for finding the maximum available bandwidth path in the multiradio multi-channel wireless mesh networks. We formally prove that the path metric is isotonic, which is the necessary and sufficient condition for assuring the proper operation of the routing algorithm. Based on the metric, we develop a routing protocol which jointly considers the path selection and the channel assignment. The time complexity of our routing algorithm is polynomial. We conduct the simulation experiments to compare the proposed metric with the existing metrics for finding the maximum available bandwidth path.
27 Oct 2011
TL;DR: It is concluded that SES is not always better than the Nash equilibrium solution (NES), further the mild and specified conditions to guarantee this optimality are provided and multiple SUs prefer to be followers in SCMG.
Abstract: We investigate the strategic behavior and analyze the performance of multiple secondary users (SUs) in a hierarchical dynamic spectrum sharing (DSS) with asymmetric information structure among them into consideration. This hierarchical DSS can be well captured using the Stackelberg capacity maximization game (SCMG) model, wherein Stackelberg equilibrium solution (SES), a potentially more effective equilibrium solution, is investigated. More importantly, we conclude that SES is not always better than the Nash equilibrium solution (NES), further the mild and specified conditions to guarantee this optimality are provided and multiple SUs prefer to be followers in SCMG. Meanwhile, closed-form power selection solutions are derived for the leader and follower players, respectively, based on which distributed algorithms in similar with iterative water-filling algorithm are designed to approximate the final SES with low implementation complexity and limited information exchange. Simulation results further verify the performance analysis and dynamic behaviors.
01 Dec 2011
TL;DR: A new method to estimate the available bandwidth of a path that considers network coding and wireless interference simultaneously simultaneously is presented and it is shown that the estimated path bandwidth can be easily achieved using a simple scheduling scheme.
Abstract: Network coding is known to be a promising technology to increase the bandwidth capacity in wireless networks. To our best knowledge, there is limited work on studying the available bandwidth for a given path with network coding. This paper presents a new method to estimate the available bandwidth of a path that considers network coding and wireless interference simultaneously. We show that our estimated path bandwidth can be easily achieved using a simple scheduling scheme. We also show that path bandwidth estimation is more accurate than other existing method through theoretical analysis and simulation experiments.
15 May 2011
TL;DR: To overcome the shortcoming of BD-VP, the proposed generalized channel inversion VP (GCI-VP) algorithms are proposed and analysis and simulation results show that the proposed ZF GCi-VP is equivalent to the BD- VP, while the algorithm MMSE GCI- VP I and MMSEGCI -VP II greatly outperform theBD-VP.
Abstract: Vector perturbation (VP) is a prominent precoding technique attracted a lot of attention in recent years. Until now, however, various extended VP techniques proposed to apply in multiuser precoding are almost restricted to one antenna configuration of each user. The restriction does not meet the development of next generation wireless systems. So, the well-known block diagonal (BD) algorithm and VP is naturally combined and proposed, named BD-VP for short, to solve this problem. However, the BD-VP completely suppressing multi-user interference (MUI) at the expense of noise enhancement results in performance degradation. To overcome the shortcoming of BD-VP, we propose generalized channel inversion VP (GCI-VP) algorithms. Analysis and simulation results show that the proposed ZF GCI-VP is equivalent to the BD-VP, while the algorithm MMSE GCI-VP I and MMSE GCI-VP II greatly outperform the BD-VP.
27 May 2011
TL;DR: In this paper, the authors deduced the optimum bandwidth ratio of the band-pass filter (BPF) for Doppler frequency shift under low SNR conditions, with which the estimation performance was always superior than 2∼5dB, comparing with current methods.
Abstract: In HF/VHF communications, the received signal is easily overwhelmed by various noise and interference signals, which has seriously affected the estimated accuracy of Doppler frequency shift, the band-pass filter (BPF) is used to suppress noise and interference effectively. Nearly everyone agrees that the more noise suppression and the more accurate the estimated results. Nevertheless, in this paper, through theoretical analysis and simulation results for the classical methods such as level crossing rate (LCR), we educe a conclusion that there exists an optimum bandwidth ratio to minimize the estimated error of Doppler frequency shift, and appropriate bandwidth noise is helpful to improve estimation performance. Therefore, in order to ensure the accuracy estimation of Doppler frequency shift under low signal-noise-ratio (SNR) conditions (γ<0dB), the optimum bandwidth ratio of BPF is deduced and determined, with which the estimation performance of proposed method is always superior than 2∼5dB, comparing with current methods.
15 May 2011
TL;DR: This work is the first proposal on assigning time slots with consideration of wireless interference and network coding simultaneously, and it is shown that this approach produces higher throughput than the existing approach.
Abstract: This paper discusses the problem of computing the maximum available bandwidth of a given path in TDMA-based network with network coding, which is a fundamental issue for supporting QoS with bandwidth requirement in wireless networks. We present a new path bandwidth computation mechanism considering physical-layer network coding. To our best knowledge, our work is the first proposal on assigning time slots with consideration of wireless interference and network coding simultaneously. Our simulation experiments show that our approach produces higher throughput than the existing approach.
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TL;DR: Simulation results show that the IIA algorithm is strictly suboptimal compared with the LOIA algorithm in the overhead-limited scenario, and extension to multiple antenna scenario is also considered.
Abstract: Based on closed-form interference alignment (IA) solutions, a low overhead distributed interference alignment (LOIA) scheme is proposed in this paper for the $K$-user SISO interference channel, and extension to multiple antenna scenario is also considered. Compared with the iterative interference alignment (IIA) algorithm proposed by Gomadam et al., the overhead is greatly reduced. Simulation results show that the IIA algorithm is strictly suboptimal compared with our LOIA algorithm in the overhead-limited scenario.
01 Sep 2011
TL;DR: Simulation results illustrate that this scheme can effectively alleviate the impairment of ICI and asymptotically approach the ICI free performance at low- to-moderate Signal-to-Noise Ratio (SNR).
Abstract: Multicarrier transmission over time varying frequency selective fading channels is investigated and a model for such a transmission scheme with emphasis on Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems is developed. The fast fading can destroy the orthogonality of subcarriers and cause serious InterCarrier Interference (ICI), thus leading to significant performance degradation that becomes severe as Doppler shift increases. To tackle this problem, a frequency domain iterative ICI mitigation algorithm is mathematically derived. By fully exploiting the separation property of Channel Transfer Function (CTF) matrix, ICI can be iteratively subtracted from received symbols and then Parallel Interference Cancellation (PIC) detection is performed to suppress multistream interference among different antennas. In particular, the complexity of the proposed strategy can be drastically reduced by restricting the interference computation to limited eighteen adjacent subcarriers, whereas the performance loss is quite minor. Simulation results illustrate that this scheme can effectively alleviate the impairment of ICI and asymptotically approach the ICI free performance at low-to-moderate Signal-to-Noise Ratio (SNR).
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TL;DR: This paper not only shows the cooperative false alarm probability and cooperative detection probability impacted by quantization, but also formulate them by two closed form expressions that enable the calculation of cooperative false alarms and Cooperative detection probability tractable efficiently, and provide a feasible approach for optimization of sensing performance.
Abstract: In cognitive radio, the cooperative spectrum sensing (CSS) plays a key role in determining the performance of secondary networks. However, there have not been feasible approaches that can analytically calculate the performance of CSS with regard to the multi-level quantization. In this paper, we not only show the cooperative false alarm probability and cooperative detection probability impacted by quantization, but also formulate them by two closed form expressions. These two expressions enable the calculation of cooperative false alarm probability and cooperative detection probability tractable efficiently, and provide a feasible approach for optimization of sensing performance. Additionally, to facilitate this calculation, we derive Normal approximation for evaluating the sensing performance conveniently. Furthermore, two optimization methods are proposed to achieve the high sensing performance under quantization.
TL;DR: A modified ISIC-MMSE detector with estimated channel state information (CSI) for bit-interleaved coded modulation (BICM) spatial multiplexing multiple input multiple output (SM-MIMO) systems is proposed.
Abstract: We study the iterative soft interference cancellation-minimum mean square error filtering (ISIC-MMSE) detector with estimated channel state information (CSI) for bit-interleaved coded modulation (BICM) spatial multiplexing multiple input multiple output (SM-MIMO) systems. By considering the channel estimation errors in all detection modules, we propose a modified ISIC-MMSE detector which considerably outperforms the conventional ISIC-MMSE detector in terms of performance and transmission rate with only moderate complexity increase.
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TL;DR: In this article, an algorithm for joint design of transmit and receive beamforming matrices is proposed to achieve more degree of freedom (DoF) compared with conventional schemes in most cases.
Abstract: For a three-cell constant cellular interfering network, a new property of alignment is identified, i.e., interference alignment (IA) solution obtained in an user-cooperation scenario can also be applied in a non-cooperation environment. By using this property, an algorithm is proposed by jointly designing transmit and receive beamforming matrices. Analysis and numerical results show that more degree of freedom (DoF) can be achieved compared with conventional schemes in most cases.
10 Oct 2011
TL;DR: This paper addresses two novel relay selection techniques: Joint Minimum Subcarrier (JMSub) and Joint Mutual Information (JMInf), for multicarrier cooperative systems when decode and forward (DF) strategy is employed, and shows that the cooperative diversity amelioration is proportional to the number of subcarriers.
Abstract: In this paper, we address two novel relay selection techniques: Joint Minimum Subcarrier (JMSub) and Joint Mutual Information (JMInf), for multicarrier cooperative systems when decode and forward (DF) strategy is employed. The theoretical outage probability or performance bound is analytically derived. Simulation results illustrate us that if the outage is defined as the probability that the sum capacity of all occupied subcarriers is smaller than some predesigned threshold, JMInf performs better; whereas if the outage probability is calculated based on respective subcarrier, the situation is opposite. Specifically, the cooperative diversity amelioration is proportional to the number of subcarriers.
15 May 2011
TL;DR: Compared with other existing routing protocols such as ZRP and MIR, the DZMRP has much higher end-to-end throughput and lower packet delivery delay due to the dramatic reduction in protocol overhead.
Abstract: In this paper, a MIMO routing protocol called as DZMRP (Double Zones MIMO Routing Protocol) for MIMO ad hoc networks was proposed. The DZMRP is a hybrid routing protocol that proactively maintains routes within a local zone of the network, which referred as the local routing zone and is divided into diversity zone and multiplex zone. Different updating frequencies of the changes of link connectivity are associated with the diversity zone and multiplex zone, so that the routing maintenance overhead is decreased dramatically. By leveraging the multiplex and diversity gains of MIMO links for the high data rate and the range extension respectively, the DZMRP improves the efficiency of a reactive route query/reply mechanism. Compared with other existing routing protocols such as ZRP and MIR, the DZMRP has much higher end-to-end throughput and lower packet delivery delay due to the dramatic reduction in protocol overhead.