Showing papers by "Jiandong Li published in 2006"
TL;DR: In this article, a boron-doped polycrystalline diamond thick film was prepared by a hot filament chemical vapor deposition (HFCVD) method and the morphology and structure of the diamond were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and micro-Raman spectroscopy.
34 citations
18 Apr 2006
TL;DR: A novel critical node detection algorithm-DMCC (detection algorithm based on midpoint coverage circle) is presented, a distributed algorithm which adapts the dynamic topology adaptively, detects the critical node faster and more reliably, and decreases the detection overheads efficiently.
Abstract: Large numbers of applications and technical mechanisms in wireless ad hoc networks requiring that the network is connected, so critical nodes, whose removal will disconnect the network into two or more separate components, will play an important role in wireless ad hoc networks. In this paper, a novel critical node detection algorithm-DMCC (detection algorithm based on midpoint coverage circle ) is presented. DMCC is a distributed algorithm which adapts the dynamic topology adaptively, detects the critical node faster and more reliably, and decreases the detection overheads efficiently.
31 citations
18 Apr 2006
TL;DR: A novel iterative parameter estimation method with interference cancellation is proposed for frequency offset and channel estimation in multi-input multi-output (MIMO) flat-fading channels and achieves a satisfactory performance.
Abstract: We address the problem of frequency offset and channel estimation in multi-input multi-output (MIMO) flat-fading channels. By considering MIMO system as equivalent single-input single-output (SISO) sub-systems with multi-antenna interference, a novel iterative parameter estimation method with interference cancellation is proposed. Numerical results show that this iterative method achieves a satisfactory performance.
15 citations
TL;DR: This work proposes a topology-transparent schedule with reservation and carrier sense based on slotted architecture in which each slot is divided into reservation phase and data phase and derives the optimal parameter for the best performance.
Abstract: To solve collisions of topology-transparent schedules in multihop ad hoc networks, we propose a topology-transparent schedule with reservation and carrier sense. Our schedule is based on slotted architecture in which each slot is divided into reservation phase and data phase. Each node resolves possible collisions in its assigned slots by reservation and utilizes free ones among its non-assigned slots by carrier sense. By analysis, we derive the optimal parameter for the best performance. Compared results show that our schedule is better than others.
13 citations
TL;DR: Through theoretical analysis, results show that the guaranteed throughput will be improved greatly by dynamic allocation of MIMO transmission capacity and its anti-interference ability.
Abstract: The transmission collisions of topology-transparent reservation time division multiple access protocol with MIMO links are solved by dynamically trading off the MIMO link transmission capacity and its anti-interference ability. Through theoretical analysis, we derive the guaranteed throughput and optimal frame length. Results show that the guaranteed throughput will be improved greatly by dynamic allocation of MIMO transmission capacity and its anti-interference ability. Moreover, the protocol is immune to topology change.
12 citations
Patent•
22 Mar 2006
TL;DR: In this article, a channel quality estimation method for continuous phase modulation self adapting frequency hopping system through referencing the extent of CPM modulation signal interfered by other signal in communication, which contains first accounting the received signal phase in one code element time and phase of standard reference signal, then accounting the phase distance between received signal and standard reference signals, finding out minimal phase distance in all signal phase possible being transmitted, taking the average value, comparing the average values with set threshold value to judge the frequency point quality.
Abstract: This invention discloses a channel quality estimation method for continuous phase modulation self adapting frequency hopping system through referencing the extent of CPM modulation signal interfered by other signal in communication, which contains first accounting the received signal phase in one code element time and phase of standard reference signal, then accounting the phase distance between received signal and standard reference signal, finding out minimal phase distance in all signal phase possible being transmitted, taking the average value, comparing the average value with set threshold value to judge the frequency point quality. Said invention can self adaptively select optimized channel to make frequency hopping communication for keeping the communication system in fine communication state.
8 citations
18 Apr 2006
TL;DR: A new online routing algorithm GLNFR (greedy and local neighbor face routing) for finding paths between the nodes of the ad hoc networks by storing a small amount of local face information at each node by using the localized Delaunay triangulation.
Abstract: With the development of ad hoc networks, some researchers proposed several geometric routing protocols which depend on the planarization of the network connectivity graph to guarantee the delivery of the packet between any pair of nodes in the network. In this paper, we proposed a new online routing algorithm GLNFR (greedy and local neighbor face routing) for finding paths between the nodes of the ad hoc networks by storing a small amount of local face information at each node. The localized Delaunay triangulation was used to be the backbone of wireless network on which the GLNFR routing algorithm runs. It has the better scalability and adaptability for the change of ad hoc networks. Experiment on NS have been conducted. The results show that the delivery rate of packets and routing protocol message cost under such novel routing protocols performs better than others proposed before.
8 citations
TL;DR: The simulation results show that, on the premise of satisfying the maximum allowable delay of packet voice, the self-adaptive transmission scheme can improve the data traffic performance and increase the WLAN capacity through dynamic and appropriate adjustment of the protocol parameters.
Abstract: The IEEE 802.11 wireless local area network (WLAN) media access control (MAC) specification is a hybrid protocol of random access and polling when both distributed coordination function (DCF) and point coordination function (PCF) are used. Data traffic is transmitted with the DCF, while voice transmission is carried out with the PCF. Based on the performance analysis of the MAC protocol for integrated data and voice transmission by simulation, this paper puts forward a self-adaptive transmission scheme to support multi-service over the IEEE 802.11 WLAN. The simulation results show that, on the premise of satisfying the maximum allowable delay of packet voice, the self-adaptive transmission scheme can improve the data traffic performance and increase the WLAN capacity through dynamic and appropriate adjustment of the protocol parameters. Especially, voice traffic is sensitive to delay jitter, and the self-adaptive scheme can effectively decrease it. Finally, it is worth noting that the adaptive scheme is easy to be realized, whereas no change in the MAC protocol is needed. Copyright © 2006 John Wiley & Sons, Ltd.
7 citations
18 Apr 2006
TL;DR: A distributed algorithm (virtual grid spatial reusing-VGSR) for MAC address assignment is presented in this paper, which is a low energy cost algorithm and reduces the size of the fixed MAC address greatly based on the mapping of geographical position.
Abstract: Compared with the small overhead of data payload in sensor network, the overhead of MAC address is significant from the point of view of energy-saving. A distributed algorithm (Virtual Grid Spatial Reusing- VGSR) for MAC address assignment is presented in this papel; which is a low energy cost algorithm and reduces the size of the fixed MAC address greatly based on the mapping of geographical position. Moreover; VGSR algorithm scales well with the network size and achieves the optimum performance by adjusting the communication range of sensor nodes. In typical scenarios, the MAC address size is 5 bits and the corresponding average size is only 3.86 bits, which outperforms other existing approaches.
4 citations
18 Apr 2006
TL;DR: A new frequency offsets estimation algorithm based on the combination of ESPRIT and the maximum likelihood (ML) estimation methods for OFDMA system is proposed, which efficiently solves the problem of multi-frequency offsets estimation.
Abstract: Carrier frequency offsets (CFOs) in orthogonal frequency division multiplexing access (OFDMA) system will introduce intercarrier interference (ICI) and consequently degrade the system performance. A new frequency offsets estimation algorithm based on the combination of ESPRIT (estimation of signal parameters by rotational invariance techniques) and the maximum likelihood (ML) estimation methods for OFDMA system is proposed. The subset of the frequency offsets is first estimated by ESPRIT then the frequency offset of each user is identified in the subset by ML estimation method. The complexity of the combination algorithm is significantly decreased compared with the ML estimator. The algorithm efficiently solves the problem of multi-frequency offsets estimation.
2 citations
TL;DR: An optimal topology-transparent reservation time division multiple access (OTTR-TDMA) protocol is proposed for multihop ad hoc networks and it is found that it gives better performance than other TDMA protocols.
01 Jun 2006
TL;DR: The simulation results show that, on the premise of satisfying the maximum allowable delay of packet voice, the self-adaptive transmission scheme can improve the data traffic performance and increase the WLAN capacity through dynamic and appropriate adjustment of the protocol parameters.
Abstract: The IEEE 802.11 wireless local area network (WLAN) media access control (MAC) specification is a hybrid protocol of random access and polling when both distributed coordination function (DCF) and point coordination function (PCF) are used. Data traffic is transmitted with the DCF, while voice transmission is carried out with the PCF. Based on the performance analysis of the MAC protocol for integrated data and voice transmission by simulation, this paper puts forward a self-adaptive transmission scheme to support multi-service over the IEEE 802.11 WLAN. The simulation results show that, on the premise of satisfying the maximum allowable delay of packet voice, the self-adaptive transmission scheme can improve the data traffic performance and increase the WLAN capacity through dynamic and appropriate adjustment of the protocol parameters. Especially, voice traffic is sensitive to delay jitter, and the self-adaptive scheme can effectively decrease it. Finally, it is worth noting that the adaptive scheme is easy to be realized, whereas no change in the MAC protocol is needed. Copyright © 2006 John Wiley & Sons, Ltd.This work was supported by National Nature Science Foundation of China under contract No. 60372048 and Microsoft Research Asia, Teaching Research Award Program for Outstanding Young Teachers in Higher Education Institutions of MOE, P.R.C., Key Project of National Nature Science Foundation of China under contract No. 60496316, Key Project of Chinese Ministry of Education under contract No. 104171, and National ‘863’ Program of China under contract No. 2001AA123031.
18 Apr 2006
TL;DR: A novel wavelet packet division multiplexing (WPDM) system based on channel equalization and Htilde matrix based on ZF (zero forcing) algorithm is studied for multipath fading channels.
Abstract: A novel wavelet packet division multiplexing (WPDM) system based on channel equalization is studied for multipath fading channels. The principle of WPDM is presented in this paper. New WPDM structures based on channel equalization and Htilde matrix based on ZF (zero forcing) algorithm are the two novel aspects of this system. The performance of the system under the multipath fading channels is analyzed
16 Aug 2006
TL;DR: The theoretical analysis and simulation results show that the proposed CRBF channel equalizer structure which uses least mean square (LMS) algorithm to obtain the optimized equalizer weights offers both fast convergence and low value of the mean square error.
Abstract: In this paper, novel wavelet packet spread spectrum (WPSS) communication system based on the complex radial basis function (CRBF) network equalizers is studied for multipath fading channels. The complex radial basis function network equalizers technique is adopted to suppress Inter-Symbol Interference (ISI) caused by multipath fading channels and reduce the symbol error rate (SER). The system performance is investigated in multipath fading channels. The theoretical analysis and simulation results show that the proposed CRBF channel equalizer structure which uses least mean square (LMS) algorithm to obtain the optimized equalizer weights offers both fast convergence and low value of the mean square error; the proposed CRBF-WPSS system has a superior SER performance to that of the conventional CRBF-OFDM-SS (spreading spectrum) system, and the proposed CRBF-WPSS system outperforms the WPSS system base on zero-forcing equalizers for multipath fading channels.