Zhang Lizhuo | University of Macau (original) (raw)

Papers by Zhang Lizhuo

Research paper thumbnail of DragonNet: A robust mobile Internet service system for long distance trains

Wide range wireless networks often suffer from annoying service deterioration due to fickle wirel... more Wide range wireless networks often suffer from annoying service deterioration due to fickle wireless environment. This is especially the case with passengers on long distance train (LDT) to connect onto the Internet. To improve the service quality of wide range wireless networks, we present the DragonNet protocol with its implementation. The DragonNet system is a chained gateway which consists of a group of interlinked DragonNet routers working specifically for mobile chain transport systems. The protocol makes use of the spatial diversity of wireless signals that not all spots on a surface see the same level of radio frequency radiation. In the case of a LDT of around 500 meters, it is highly possible that some of the spanning routers still see sound signal quality, when the LDT is partially blocked from wireless Internet. DragonNet protocol fully utilizes this feature to amortize single point router failure over the whole router chain by intelligently rerouting traffics on failed ones to sound ones. We have implemented the DragonNet system and tested it in real railways over a period of three months. Our results have pinpointed two fundamental contributions of DragonNet protocol. First, DragonNet significantly reduces average temporary communication blackout (i.e. no Internet connection) to 1.5 seconds compared with 6 seconds that without DragonNet protocol. Second, DragonNet efficiently doubles the aggregate throughput on average.

Research paper thumbnail of Wireless Access Point Deployment for Both Coverage and Localization

ABSTRACT Wireless access points (APs) divide a plane into small areas where their coverage ranges... more ABSTRACT Wireless access points (APs) divide a plane into small areas where their coverage ranges overlap. A mobile device can be located within a particular small overlapped area based on the unique set of APs covering the device. We formally define an optimal AP deployment problem for both coverage and area localization. Our objective is to deploy a minimum number of APs that provide full communication coverage while achieving the ability to locate a mobile device within a certain area no larger than a given accuracy parameter. We propose a set of optimal solutions and approximations to this problem under the diamond pattern, a deployment pattern that has been shown to achieve optimal coverage in most cases. We conduct extensive numerical evaluation as well as real experiments to validate our proposed solutions.

Research paper thumbnail of Two Birds With One Stone: Wireless Access Point Deployment for Both Coverage and Localization

IEEE Transactions on Vehicular Technology, 2011

Wireless access points (APs) divide a plane into small areas where their coverage ranges overlap.... more Wireless access points (APs) divide a plane into small areas where their coverage ranges overlap. A mobile device can be located within a particular small overlapped area based on the unique set of APs covering the device. We formally define an Optimal Loc-deployment problem for both coverage and area localization. Our objective is to deploy a minimum number of APs that provide full communication coverage while achieving the ability to locate a mobile device within a certain area no larger than a given accuracy parameter. We obtain a formula that precisely determines the optimal solution for more than half of the accuracy values. For the rest of the accuracy values, we propose an algorithm that will return an approximation whose difference to the optimal solution is less thanfor any �> 0. Finally, we conduct extensive numerical evaluation and real experiments to validate our proposed solutions.

Research paper thumbnail of One Stone Two Birds: Wireless Access-Point Deployment for Both Coverage and Localization

Wireless access-points (AP) will divide a plane into small areas when their coverage ranges overl... more Wireless access-points (AP) will divide a plane into small areas when their coverage ranges overlap. A mobile device can be located within a particular small overlapped area based on the unique set of APs covering the device. We formally define an optimal AP deploy- ment problem for both coverage and area localization. Our objective is to deploy a least number of APs that provide full communication coverage while achieving the ability of locating a mobile device within a certain area no larger than a given accuracy parameter. We propose a set of optimal and approximation solutions to this problem. We conduct extensive numerical evaluation as well as real experiments to validate our proposed solutions.

Research paper thumbnail of Performance Analysis of the Contention Resolution Scheme in IEEE 802.16

Journal of Software, 2007

Research paper thumbnail of Research of TCP NAT Traversal Solution Based on Port Correlation Analysis & Prediction Algorithm

ABSTRACT Although solutions have been proposed for NAT traversal in UDP based P2P applications, T... more ABSTRACT Although solutions have been proposed for NAT traversal in UDP based P2P applications, TCP based NAT traversal still remains challenges due to the relatively complicated protocols. In this paper, we propose a Port Correlation Analysis and Prediction (PCAP) algorithm to predict the NAT allocated port number and a novel PCAP based TCP NAT traversal scheme to build successful P2P connections. We evaluate our method through experiments under real networking environments. The results demonstrate the effectiveness of PCAP algorithm on NAT behavior detection and port prediction and the system achieves higher successful P2P connection rate.

Research paper thumbnail of Binomial Probability Redundancy Strategy for Multimedia Transmission

This paper proposes a Binomial Probability Redundancy Model (BPRM). This model is based on the Fo... more This paper proposes a Binomial Probability Redundancy Model (BPRM). This model is based on the Forward Error Correction (FEC) Reed-Solomon Coding Technique and the Interweaving Packet Loss Recovery Technique. It calculates the number of redundant packets according to the feedback from the receiver and dynamically generates these superfluous packets. Different from the Linear Probability Redundancy Model (LPRM) proposed by McKinley et al., we adopt the interweaving technique to transmit these redundant packets.

Research paper thumbnail of Performance Improvement using Dynamic Contention Window Adjustment for Initial Ranging in IEEE 802.16 P2MP Networks

Abstract∗–In IEEE 802.16 networks, initial ranging is a primary and important procedure of connec... more Abstract∗–In IEEE 802.16 networks, initial ranging is a primary and important procedure of connection setup between subscribe stations and base station. The mandatory method defined in the standard of contention resolution is based on a truncated binary exponential backoff, with a fixed ...

Research paper thumbnail of Video surveillance patrol robot system in 3G, Internet and sensor networks

We propose to demo a ubiquitous surveillance patrol robot system1which can patrol in a candidate ... more We propose to demo a ubiquitous surveillance patrol robot system1which can patrol in a candidate site to per- form events detection where a wireless sensor network may be deployed. We have enabled the 3G phone controlled pa- trol robot (over 3G circuit switched network) with integrated access to the WiFi/Internet. Internet is used to provide sensor query, to send control

Research paper thumbnail of Local Retransmission-Based Gossip Protocol in Mobile Ad Hoc Networks

Abstract The node mobility makes it difficult to guarantee a high reliability of data delivery fo... more Abstract The node mobility makes it difficult to guarantee a high reliability of data delivery for existing multicast routing protocols, but it is a major concern in protocol design for mobile ad-hoc networks (MANETs). We propose a novel scalable and reliable multicast protocol ...

Research paper thumbnail of Design and Implementation of Instant Message System Based on 3G

Research paper thumbnail of DragonNet: A robust mobile Internet service system for long distance trains

Wide range wireless networks often suffer from annoying service deterioration due to fickle wirel... more Wide range wireless networks often suffer from annoying service deterioration due to fickle wireless environment. This is especially the case with passengers on long distance train (LDT) to connect onto the Internet. To improve the service quality of wide range wireless networks, we present the DragonNet protocol with its implementation. The DragonNet system is a chained gateway which consists of a group of interlinked DragonNet routers working specifically for mobile chain transport systems. The protocol makes use of the spatial diversity of wireless signals that not all spots on a surface see the same level of radio frequency radiation. In the case of a LDT of around 500 meters, it is highly possible that some of the spanning routers still see sound signal quality, when the LDT is partially blocked from wireless Internet. DragonNet protocol fully utilizes this feature to amortize single point router failure over the whole router chain by intelligently rerouting traffics on failed ones to sound ones. We have implemented the DragonNet system and tested it in real railways over a period of three months. Our results have pinpointed two fundamental contributions of DragonNet protocol. First, DragonNet significantly reduces average temporary communication blackout (i.e. no Internet connection) to 1.5 seconds compared with 6 seconds that without DragonNet protocol. Second, DragonNet efficiently doubles the aggregate throughput on average.

Research paper thumbnail of Wireless Access Point Deployment for Both Coverage and Localization

ABSTRACT Wireless access points (APs) divide a plane into small areas where their coverage ranges... more ABSTRACT Wireless access points (APs) divide a plane into small areas where their coverage ranges overlap. A mobile device can be located within a particular small overlapped area based on the unique set of APs covering the device. We formally define an optimal AP deployment problem for both coverage and area localization. Our objective is to deploy a minimum number of APs that provide full communication coverage while achieving the ability to locate a mobile device within a certain area no larger than a given accuracy parameter. We propose a set of optimal solutions and approximations to this problem under the diamond pattern, a deployment pattern that has been shown to achieve optimal coverage in most cases. We conduct extensive numerical evaluation as well as real experiments to validate our proposed solutions.

Research paper thumbnail of Two Birds With One Stone: Wireless Access Point Deployment for Both Coverage and Localization

IEEE Transactions on Vehicular Technology, 2011

Wireless access points (APs) divide a plane into small areas where their coverage ranges overlap.... more Wireless access points (APs) divide a plane into small areas where their coverage ranges overlap. A mobile device can be located within a particular small overlapped area based on the unique set of APs covering the device. We formally define an Optimal Loc-deployment problem for both coverage and area localization. Our objective is to deploy a minimum number of APs that provide full communication coverage while achieving the ability to locate a mobile device within a certain area no larger than a given accuracy parameter. We obtain a formula that precisely determines the optimal solution for more than half of the accuracy values. For the rest of the accuracy values, we propose an algorithm that will return an approximation whose difference to the optimal solution is less thanfor any �> 0. Finally, we conduct extensive numerical evaluation and real experiments to validate our proposed solutions.

Research paper thumbnail of One Stone Two Birds: Wireless Access-Point Deployment for Both Coverage and Localization

Wireless access-points (AP) will divide a plane into small areas when their coverage ranges overl... more Wireless access-points (AP) will divide a plane into small areas when their coverage ranges overlap. A mobile device can be located within a particular small overlapped area based on the unique set of APs covering the device. We formally define an optimal AP deploy- ment problem for both coverage and area localization. Our objective is to deploy a least number of APs that provide full communication coverage while achieving the ability of locating a mobile device within a certain area no larger than a given accuracy parameter. We propose a set of optimal and approximation solutions to this problem. We conduct extensive numerical evaluation as well as real experiments to validate our proposed solutions.

Research paper thumbnail of Performance Analysis of the Contention Resolution Scheme in IEEE 802.16

Journal of Software, 2007

Research paper thumbnail of Research of TCP NAT Traversal Solution Based on Port Correlation Analysis & Prediction Algorithm

ABSTRACT Although solutions have been proposed for NAT traversal in UDP based P2P applications, T... more ABSTRACT Although solutions have been proposed for NAT traversal in UDP based P2P applications, TCP based NAT traversal still remains challenges due to the relatively complicated protocols. In this paper, we propose a Port Correlation Analysis and Prediction (PCAP) algorithm to predict the NAT allocated port number and a novel PCAP based TCP NAT traversal scheme to build successful P2P connections. We evaluate our method through experiments under real networking environments. The results demonstrate the effectiveness of PCAP algorithm on NAT behavior detection and port prediction and the system achieves higher successful P2P connection rate.

Research paper thumbnail of Binomial Probability Redundancy Strategy for Multimedia Transmission

This paper proposes a Binomial Probability Redundancy Model (BPRM). This model is based on the Fo... more This paper proposes a Binomial Probability Redundancy Model (BPRM). This model is based on the Forward Error Correction (FEC) Reed-Solomon Coding Technique and the Interweaving Packet Loss Recovery Technique. It calculates the number of redundant packets according to the feedback from the receiver and dynamically generates these superfluous packets. Different from the Linear Probability Redundancy Model (LPRM) proposed by McKinley et al., we adopt the interweaving technique to transmit these redundant packets.

Research paper thumbnail of Performance Improvement using Dynamic Contention Window Adjustment for Initial Ranging in IEEE 802.16 P2MP Networks

Abstract∗–In IEEE 802.16 networks, initial ranging is a primary and important procedure of connec... more Abstract∗–In IEEE 802.16 networks, initial ranging is a primary and important procedure of connection setup between subscribe stations and base station. The mandatory method defined in the standard of contention resolution is based on a truncated binary exponential backoff, with a fixed ...

Research paper thumbnail of Video surveillance patrol robot system in 3G, Internet and sensor networks

We propose to demo a ubiquitous surveillance patrol robot system1which can patrol in a candidate ... more We propose to demo a ubiquitous surveillance patrol robot system1which can patrol in a candidate site to per- form events detection where a wireless sensor network may be deployed. We have enabled the 3G phone controlled pa- trol robot (over 3G circuit switched network) with integrated access to the WiFi/Internet. Internet is used to provide sensor query, to send control

Research paper thumbnail of Local Retransmission-Based Gossip Protocol in Mobile Ad Hoc Networks

Abstract The node mobility makes it difficult to guarantee a high reliability of data delivery fo... more Abstract The node mobility makes it difficult to guarantee a high reliability of data delivery for existing multicast routing protocols, but it is a major concern in protocol design for mobile ad-hoc networks (MANETs). We propose a novel scalable and reliable multicast protocol ...

Research paper thumbnail of Design and Implementation of Instant Message System Based on 3G