Harold Zheng

A resource management design for cognitive radio ad hoc networks

To fully utilize radio resources by intelligently filling in as much radio spectrum gaps as possible, the concept of cognitive radio network has been well accepted. A challenge inherent in this technology is how to build a mechanism that can allocate resource by learning and adapting to a specific radio transmission environment. In this paper, we propose a cognitive resource management scheme that is specifically designed for allocating radio resource in a cognitive radio ad hoc network (CRAHN) environment. The proposal applies cognitive processes in a cross-layer design, which acquires knowledge from the physical layer, the medium access control (MAC) layer, and application layer. It intelligently allocates resources according to traffic demands, traffic priorities, link capabilities, and link qualities.

A QoS enhanced hybrid SR-ARQ for mobile video communications

A hybrid QoS aware SR-ARQ (HQSR-ARQ) is proposed to increase the network throughput for video delivery in a bandwidth limited and error prone wireless mobile environment with certain deterministic guarantees. HQSR-ARQ balanced the pros and the cons of the conventional SR-ARQ and FEC for error control. It also utilized the layer property of MPEG to provide more network resources for important data sections within a video stream. Comprehensive computer simulations were used to compare the performance of HQSR-ARQ with a conventional SR-ARQ and the original QSR-ARQ in terms of the same QoS matrix. The results demonstrated the effectiveness and performance improvement of HQSR-ARQ.

SIP-based VoIP experiment for sisadvantaged tactical edge networks

Session Initiation Protocol (SIP) has potential to be selected as a control plane signaling protocol for delivering real-time multimedia applications in military networks. It is necessary to study behaviors of SIP and SIP-based real-time applications as well as to understand their limitations in a tactical network environment. The goals of this study are to assess SIP signaling protocol performance and SIP-based Voice over Internet Protocol (VoIP) performance in an emulated disadvantaged tactical edge network environment and to contribute some feasible solutions.

QoS Management in Disadvantaged Tactical Environments

The tactical Network is one of the major components in DoD Global Information Grid (GIG). The key challenge of quality of service (QoS) management tactical networks is how to deal with negative factors that result from varying network capability demanding and a disadvantaged physical environment. These factors could include network mobility, dynamic network formation, unusual network protocol behaviors, communication channel fading, channel bandwidth fluctuation, as well as platform/application characteristics. This paper investigates the challenges of several well-known QoS management mechanisms in disadvantaged tactical network environments and provides some recommendations on the directions of mitigations and improvements.

QoS constrained resource allocation for multimedia wireless networks

To deliver high bandwidth demanding video traffic over the resource limited wireless systems is becoming a challenge issue. To control quality of service (QoS) of the delivery is even more difficult. A QoS constrained multilevel resource allocation scheme (QML-RA) is proposed to tackle the problem of how to flexibly allocate wireless network resources for carrying video traffic with certain QoS guarantees. This scheme utilizes the layer property of MPEG frames and considers the QoS requirements of different data sections within a video stream. It also takes the advantage of the channel allocation flexibility provided by CDMA/TDD systems and statistically assigns bandwidth to video traffic according to their QoS requirements. Moreover, an optimal smoothing technique is used to preprocess the video traffic so that bit-rate variability could be reduced, which enhances performance of QML-RA. The scheme significantly improves the channel utilization and increases the network throughput.

Reliable Session Initiation Protocol

The IP Multimedia Subsystem (IMS) is a maturing technology. It has the potential to be used in Mobile Ad Hoc Networks (MANETs) to provide multimedia Internet experience for much diversified users with a variety of applications in a highly mobile environment. The introduction of the IMS into MANETs and futuristic mobile networks face unique challenges and needs. The underlying signalling protocol for the IMS is the Session Initiation Protocol (SIP). In this chapter, we first investigate the “unreliable signalling” problem of using SIP for mobility support. Based on the investigation and the analysis, this chapter introduces an enhanced SIP signalling mechanism called Chain-Based SIP signalling (CBS) to mitigate the problem. The analytical performance analysis results will be given in the chapter as well.

Multi-Plane Network Model Realization in an Optical/RF Hybrid System

To facilitate the Quality of Service (QoS) interoperability, a multi-plane end-to-end (E2E) QoS architecture reference model has been developed. This modelprovides a network-functional-plane-based QoS architecture and defines different interfaces for composing a coherent data transfer and management. In this model, QoS functions are categorized into Data Plane, Control Plane, and Management Plane. However, a lack of sufficient network resource hinders the support for such sophisticated network architecture. A major mitigation approach is to implement an optical/Radio Frequency (RF) hybrid system. This paper proposes a resource management scheme for an optical/RF hybrid system and looks into the realization of multi-planes model in this hybrid system that supports an acceptable QoS level.

Advanced communication framework for video quality in public safety

The Third Generation Partnership Project (3GPP) Long-term Evolution (LTE) cellular network technology was selected as the basis for the Nationwide Public Safety Broadband Network (NPSBN). Deployment of the nations first high-speed broadband network for public safety should be strategically planned and considered to avoid potential operational issues, especially for video. The demand for the video services would likely be high, especially during emergencies, requiring efficient management of the limited supply of LTE resources. Though capabilities and capacities of 4th generation (4G) LTE networks are a significant improvement over earlier generation radio access technologies, the network resources are still expected to be limited, especially during emergency incidents with higher demand. The resources required to support video over wireless networks are significant. Thus, research is needed to determine the efficient utilization of NPSBN bandwidth for video content transmission. After providing relevant background on video data and LTE networks, this paper proposes an advanced communication framework of the Mission, Content, and Transport network (MCTn) for considering the wireless video transmission in a holistic fashion. The MCTn framework conceptualizes: 1) the Mission requirements that define the video quality requirement for the intended purpose and priority of the intended end user(s) to be successful in completing the operational objectives; 2) the owners responsibility to capture and package video Content efficiently for distribution to the end user based on the mission needs; 3) the operators responsibility for the Transport network to understand priority and video quality requirements of the mission and utilize features available on the LTE network to prioritize and deliver video to the intended end user(s) during times of congestion or peak demand. The conclusion of this paper provides recommendations on areas for additional study.

Reliability enhancement for SIP signaling in tactica environments

The importance of tactical networks that support military operations is well known in the DoD community for their ability to rapidly deploy anywhere at anytime without pre-existing infrastructure. Tactical networks provide a battle space where warfighters possess dynamic and ad hoc mobile communications to support operations against a broad array of threats. Managing mobility to provide undisrupted network connectivity to support continuous operation is a fundamental component of tactical networks. This study proposes a reliability enhancement for SIP mobility support.

Enhanced IP Multimedia Subsystem (IMS) for futuristic tactical networks

A critical element of the all-IP architecture is IP multimedia subsystem (IMS). IMS is a maturing technology and has been standardized by wireless cellular industry. However, IMS was not designed and developed for using in military environments and supporting associated application services. Introducing IMS into futuristic military networks for supporting future combats has to face different challenges. In this paper, the authors explain advantages and challenges of using IMS for supporting multimedia experience in tactical environments. The paper proposes an enhancement to improve IMS performability.