Yang Xiao-zong

A sniff scheduling policy for power saving in Bluetooth piconet

After deeply analyzing sniff mode which is a low power operation mode of Bluetooth, a learning function is used to approximate the distribution of the incoming traffic at a master-slave pair. Based the inter-arrival times of data packets obtained from the learning function, the mean of these inter-arrival times is the possible sniff interval; according to the backlog packets in the buffer space and forecast next burst data traffic, a cost model is used to approximate the slot occupancy assigned to a slave. Consequently, calculate sniff attempt slots, and go into sniff mode if conditions are satisfied. Finally, computer simulation results validate that the proposed scheduling policy can save about 38.6% power consumption compared to the always active mode.

Performance Comparison with Different Pulse Waveforms in Ultra-wideband Based Wireless Sensor Networks

Recently approved IEEE 802.15.4a standard defines an ultra-wideband (UWB) based physical layer technique, and performance analysis of UWB systems shows that the pulse waveform will affect the received SINR when multipath interference, multiple access interference and additive white Gaussian noise are considered. In order to obtain an optimal pulse waveform in UWB based wireless sensor networks, the normalized SNR is firstly proposed without the effect of pulse waveform, and then three pulse waveforms are analyzed and compared in different channels. Finally, the critical value of normalized SNR for different pulse waveforms is drawn with different transmission data rates and user numbers. Results show that the performance of UWB systems is affected by power efficiency and correlation property of transmitted pulse waveform together. And the pulse with high power efficiency shows better performance in low SNR, and the pulse with good correlation property shows better performance in high SNR.

DPHM： A FAULT DETECTION PROTOCOL BASED ON HEARTBEAT OF MULTIPLE MASTER-NODES

In most of fault detection algorithms of distributed system, fault model is restricted to fault of process, and link failure is simply masked, or modeled by process failure. Both methods can soon use up system resource and potentially reduce the availability of system. A fault Detection Protocol based on Heartbeat of multiple Master-nodes (DPHM) is proposed, which can immediately and accurately detect and locate faulty links by adopting voting and electing mechanism among master-nodes. Thus, DPHM can effectively improve availability of system. In addition, in contrast with other detection protocols, DPHM reduces greatly the detection cost due to the structure of master-nodes.

Redundant Multithreading Architecture Overview

To overcome the ever-increasing susceptibility to transient-fault in processors, various redundant multithreading (RMT) architectures have been proposed, which is becoming a most effective approach for detecting and recovering from transient-fault. This paper surveys a wide range of RMT architectures—from the original AR-SMT(A-stream R-stream Simultaneous MultiThreading) to the most-recent SD-SRT (Slack-Decode Simultaneous Redundant Threading), presenting traverse analyses and comparisons among them, and hereby demonstrates its evolution and tendency. Finally, some directions and suggestions are put forward for the further RMT research and development.

PatchPSMP: an extension of NSMP based on pool node

As an extension of NSMP (neighbor supporting multicast protocol), PatchPSMP not only inherits the advantages of NSMP [Seungjoon Lee et al., 2000] and PatchODMRP [Meejeong Lee et al., 2001], but also has its own characters. Therefore, PatchPSMP has the following characters: (1)its route setting up and evaluation policy is same as that of NSMP; (2)its local recovery method is same as that of PatchODMRP; (3)it defines the unforwarding neighbor of forwarding nodes as pool nodes to collect the route information from its received data packets to reduce its local route recovery scope further. When a forwarding node finds a link failure between it and one of its upstream nodes, it floods out an ADVT packet. A pool node can answer its received ADVT packet when it connects to the wanted sources defined in the ADVT packet. By the simulation, we compare the performance of these protocols. PatchPSMP outperforms the others.

PatchPSMP: A new multicast protocol for ad-hoc network

As a new Ad Hoc multicast protocol, PatchPSMP (Patch Pool-Supporting Multicast Protocol) extends NSMP (Neighbor Supporting Multicast protocol) [1] not only by adopting the local recovery method of PatchODMRP [2], but also defining the pool nodes to reduce its local recovery scope further. By the simulations, we compare the performance of NSMP, PatchODMRP and PatchPSMP. PatchPSMP outperforms the other two protocols. Especially when there are many senders in the group, its improvement is more outstanding.

TRSTR: A Fault.Tolerant Microprocessor Architecture Based on SMT

Based on Simultaneous Multithreading (SMT), we propose a fault-tolerant scheme called Tri-modular Redundantly and Simultaneously Threaded processor with Recovery (TRSTR). TRSTR features as following: First, we introduce an arbitrator context into the conventional SRT (Simultaneous and Redundantly Threaded), which acts as an arbitrator when results from the other two contexts disagree, or acts as an ordinary thread generally, thus making full use of SMTs parallelism. Second, we append reconfigurable feature to sphere of replication in SRT, making it more flexible for changing demands and situations. Third, TRSTR has two working modes: Tri-Simultaneous with Voting (TSV) and Dual-Simultaneous with Arbitrator (DSA), which can switch at will. Finally, in addition to transient-fault coverage, TRSTR has on-line self-checking and self-recovering abilities, so as to shield off some permanent faults and reconfigure itself without stopping the crucial job, improving its reliability and availability.

Performance analysis of UWB based wireless sensor networks in indoor office LOS environment

With the fast development of wireless sensor networks (WSN), more attentions are paid to high data rate transmission of WSN, and hence, in IEEE 802.15.4a standard, ultra-wideband (UWB) is introduced as one of the physical layer technique to support high transmission data rate and precisie locationing applications. In order to analyze the bit error rate (BER) performance of UWB based WSN, a system model considering intra-symbol interference (IASI), inter-symbol interference (ISI), multiuser interference (MUI) and addictive white Gaussian noise (AWGN) is proposed in this paper, and then verified using simulation results. Moreover, the pulse waveforms complying with the spetrum requirement of IEEE 802.15.4a standard are given, and based on such obtained pulses, the effect of transmission data rate and user number is also shown. Results show that with the increase of SNR, the intra-symbol interference will decrease the system performance significantly, and system performance can be improve by using pulse waveforms with little intra-symbol interference.

A scheduling scheme with Dynamic Frequency Clocking and multiple voltages for low power designs

In this letter, a scheduling scheme based on Dynamic Frequency Clocking (DFC) and multiple voltages is proposed for low power designs under the timing and the resource constraints. Unlike the conventional methods at high level synthesis where only voltages of nodes were considered, the scheme based on a gain function considers both voltage and frequency simultaneously to reduce energy consumption. Experiments with a number of DSP benchmarks show that the proposed scheme achieves an effective energy reduction.

One Hop-DAD based address autoconfiguration in MANET6

Mobile ad hoc networks (MANETs) are autonomous and infrastructureless networks that support multi-hops wireless communications among mobile hosts. Autoconfiguration of hosts is an important open problem in self-organizing MANETs. Additionally, providing global Internet connectivity to MANETs is a strong trend nowadays, so the mobile hosts must be configured with a global IP address. In this paper, we propose an IPv6 address autoconfiguration protocol which uses mobile host’s geographic location information and time information gained from GPS receiver as the unique metrics to construct the unique Interface ID of IPv6 address. This addressing protocol makes the duplicate address detection (DAD) operation be bounded in one hop broadcast, so we call it as “one hop-DAD”, which reduces the overhead of address configuration and the address allocation latency very much.