Zhang Hong-ke

A Pattern matching based Network Intrusion Detection System

Intrusion detection system (IDS) has recently become a heated research topic due to its capability of preventing attacks from malicious network users. A pattern matching intrusion detection system has been proposed in this paper. The pattern matching based NIDS consists of four modules: collection module, analyze module, response module and attack rule library. We base this system on CIDF architecture. Realizing that string matching is the bottleneck, our system has improved the performance of detection engines due to an improved algorithm based on the current BM algorithm. Testing results demonstrate superior performance in terms of the detection speed of IDS

The effect of human activites on 2.4 GHz radio propagation at home environment

As the technology evolves, Wireless Sensor Networks (WSNs) for home environment, such as healthcare systems, can be designed using low-cost, low-power and short-range radio equipments in 2.4GHz ISM Frequency-band. While a great deal of efforts have been paid for studying the radio fading caused by human body in WLAN or cellular-systems, however, the comprehensive effects of the human mobility on WSNs radio propagation for indoor environment remain unexplored widely. In this paper, we investigate the effects of human activities on the radio propagation of wireless sensor networks at home, based on the experimental measurements. Our results show that these factors have significantly effect on the receive radio signal strength. We also propose an improved radio propagation model to characterize the mobility of people for the effects of indoor radio propagation of wireless sensor networks. As an example, the random way point model is employed as the mobility model. The evaluation results show that our model performs better coherence with the measurement results.

Modeling in hierarchical mobile IPv6 and intelligent mobility management scheme

Decreasing communication and management cost is a key issue of the research of Internet mobility management. Hierarchical mobile IPv6 (HMIPv6) has been proposed to reduce the number of location registration messages in backbone network by using hierarchy agent, but resources consumption inside the hierarchical domain is increased as expense. In this paper, a concept of integrated optimization is proposed, in which network cost and bandwidth consumption of delivering management messages and data payload is optimized both inside and outside hierarchical domain in a certain degree. Mathematic models of HMIPv6 are built on the viewpoint of entire network resource, and the judgment rule is obtained in result, which determines when HMIPv6 is adopted preferably. Based on the rule, intelligent mobility management scheme (IMMS) is designed, which allows a mobile node to select a suitable mobility management mechanism from mobile IPv6 and HMIPv6 according to its working parameters. Only mobile nodes protocol stack needs to be changed in IMMS and co-operation ability is assured.Decreasing communication and management cost is a key issue of the research of Internet mobility management. Hierarchical mobile IPv6 (HMIPv6) has been proposed to reduce the number of location registration messages in backbone network by using hierarchy agent, but resources consumption inside the hierarchical domain is increased as expense. In this paper, a concept of integrated optimization is proposed, in which network cost and bandwidth consumption of delivering management messages and data payload is optimized both inside and outside hierarchical domain in a certain degree. Mathematic models of HMIPv6 are built on the viewpoint of entire network resource, and the judgment rule is obtained in result, which determines when HMIPv6 is adopted preferably. Based on the rule, intelligent mobility management scheme (IMMS) is designed, which allows a mobile node to select a suitable mobility management mechanism from mobile IPv6 and HMIPv6 according to its working parameters. Only mobile nodes protocol stack needs to be changed in IMMS and co-operation ability is assured.

Status-aware resource adaptation in information-centric and software-defined network

In recent years, realising a “clean-state” design for the future Internet has become an important research focus. An architecture combining an Information-Centric Network (ICN) and Software-Defined Network (SDN) (IC-SDN) has gradually attracted more attention. However, the existing studies regarding IC-SDN still lack support in terms of the “network status awareness” function, resulting in unreasonable resource allocation. In this paper, we propose a new status-aware resource adaptation scheme, i.e. a status-aware module is embedded into basic elements (Forwarding Node (FN) and Resource adaption Manager (RM)). The FNs collect the network status dynamically for the controller to reallocate network resources according to the fluctuations in environmental conditions. Simulation results show that, compared with the existing IC-SDN mechanism, the proposed scheme reduced the link bandwidth variance by 56% and the content delivery latency by 40%. The proof-of-concept implementation demonstrates the feasibility of our proposed scheme for small-scale deployment.

Throughput modeling analysis of IEEE 802.11 DCF mechanism in multi-hop non-saturated wireless ad-hoc networks

Medium access control (MAC) protocols have a large impact on the system performance for wireless ad hoc networks. Because of the limitations of existing analytical models for ad hoc networks, many researchers have to study the impact of MAC protocols via discrete simulations. In this paper, in order to improve this disadvantage, we provided an analytical model to compute of 802.11 DCF wireless multi-hop networkspsila throughput, with the assumption of finite number of terminals. This analytical model considers wireless network MAC layer in multi-hop non-saturated situation and also quantitatively computes the function of packet discard ratio factor. The simulation result shows that even in multi-hop situation, this network throughput model is still matching well with the actual wireless Ad-Hoc networks.

Small Cell Deployment and Smart Cooperation Scheme in Dual-Layer Wireless Networks

Traditional mobile networks will become dual-layer wireless networks due to small cells’ deployment. The advantages of dual-layer networks are improving network capacity and overcoming the problem of unbalanced traffic distribution in time-space domain. In this paper, performance of small cells deployment is evaluated in simulations. It is shown that users’ traffic is offloaded by small cells obviously. At the same time, performances of signal to interference plus noise ratio (SINR) and throughput are also improved. However, low SINR ( SINR < 10  dB) users are also increased because of interferences between macro cells and small cells. Furthermore, a new cooperation scheme is proposed for energy saving in dual-layer networks. This scheme is implemented through a functional modular, named by Area Control Center (ACC). Finally, simulations are given to verify the efficiency of this energy saving scheme. The numerical results show that energy consumption could be reduced by 20%.

Reducing maintenance overhead via heterogeneity in Skip Graphs

Skip Graphs provide novel distributed data structures for peer-to-peer (P2P) searching. They are simple, resilient and are capable of supporting complex queries. Like many distributed hash table (DHT) algorithms, one issue that remains to be addressed is the large number of pointers per node in the system. They suffer from the problems of high storage requirements and high volume of repair-mechanism message traffic. In addition, nodes are treated equally in Skip Graphs, but empirical studies have shown that peers in P2P networks are heterogeneous. Some nodes are more powerful and stable than the others. In order to solve these problems, we propose the Skip Graphs++, which gives an adaptive node capacity model to evaluate the performance of nodes in the system and builds the relationship between the loads and the capacities of nodes. In Skip Graphs++ system the loads are proportional to the capacities of nodes. Powerful nodes afford more loads and weak nodes afford fewer loads. Theoretical and experimental results have shown that the maintenance overhead is reduced efficiently via heterogeneity.

Fairness evaluation of the default highspeed TCP in common operating systems

Since the TCP protocol implements in the internet, the AIMD algorithm has always been the dominating congest control algorithm for about 20 years, and most of the common operating systems follow the recommendation of the IETF to adopt the AIMD algorithm in their TCP variations. But in recent years, many high-speed congest control algorithms have been proposed for fast data transfer over high speed and long distance networks, and many operating systems take the high-speed TCP variations as default: the Linux kernel uses CUBIC TCP as default since version 2.6.18, while Compound TCP becomes default TCP in Windows Server 2008 and a part of Microsoft Windows Vista, where it is easy to be enabled. As there are still not sufficient and comprehensive performance comparison of the high-speed TCP variations, the deployment of them as default TCP in the operating systems raises concerns about the future of congest control in the internet and worries about the fairness problem. This paper is an attempt to evaluate the fairness of the default TCP in the newest Linux and Microsoft Windows. The simulation results indicate that between CUBIC TCP and Compound TCP it indeed exhibits unfairness. The CUBIC TCP is too aggressive to the Compound TCP in the high bandwidth-delay product network, and the performance of Compound TCP is unacceptable comparing to CUBIC TCP.

Environmental monitoring and air-conditioning automatic control with intelligent building wireless sensor network

Wireless sensor network (WSN) is the connection between the physical world and mankind. Particularly, environmental monitoring and devices automatic control of intelligent building based on wireless sensor network is considered as one of the most crucial applications. It can perceive many kinds of environmental parameters and feedback control information to some devices to provide comfortable environment to people. However, it is difficult to deploy a WSN in the buildings because there usually are many wireless LAN devices used in the buildings, which bring serious frequency interferences. In this paper, we conduct a real intelligent building wireless sensor network (IBWSN) for environmental monitoring and air-conditioning automatic control. In order to ensure the effectiveness of this system, actual spectrum analysis is developed. Performance evaluation proves that the presented IBWSN can satisfy the needs of the proposed applications.

An adaptive distributed hybrid search scheme for unstructured peer-to-peer networks

We consider a distributed hybrid search scheme for peer-to-peer network in this paper and introduce one link statement function, which is decreasing with the round trip time (RTT) of link. Link statement function is reasonable because they can reflect how well the link worked, for example, overloaded or not. The transition probability function between two nodes is redefined, which depend on not only the association of these two nodes but also the link statement between them. So one node can choose its best neighbor based on the transition probability between them to forward the query message. This algorithm is more robust and adaptive to the dynamic networks.