Shaowei Liu

A general framework of multipath transport system based on application-level relay

Multipath transport has been shown to be an effective way to improve the efficiency of data delivery. However, current multipath transport methods either only apply to a specific kind of applications, or require specific network setting of terminal devices or behaviors of network devices. This paper presents a general framework of multipath transport system based on application-level relay (MPTS-AR), currently under the standardization within the IETF. The MPTS-AR framework defines three kinds of logical entities including user agent, relay and controller. It also defines a relay service control protocol named OpenPath in control plane to manage relay paths, and a profile of multipath transport protocol (MPTP) suite in data plane to facilitate multipath data transport. MPTP protocol suite is to meet the transmission requirements of various upper applications. This paper also illustrates how to apply the MPTS-AR framework to multimedia applications based on real-time transport protocol (RTP).

Architecture and Key Issues of IMS-Based Cloud Computing

Cloud computing is changing the way of developing, deploying and managing applications. However, as typical Internet-based applications, cloud computing services lack carrier-grade signaling control mechanism and cannot guaranty Quality of Service (QoS), which have actually become technical barriers for telecom operator to provide commercial public cloud services. On the other hand, as the core signaling architecture of Next Generation Networking (NGN), IP Multimedia Subsystem (IMS) is facing the problem of the lack of innovative value-added services. This paper presents an architecture to support cloud computing services over IMS. In the proposed architecture, cloud services are regarded as the general IMS applications and then cloud clients are allowed to access cloud services under the control of Session Initiation Protocol (SIP) signaling and QoS mechanism of IMS. This paper introduces architecture overview and cloud service relevant functional components, and mainly discusses several key issues including cloud notification mechanism, QoS and charging control of IMS-based cloud computing services.

The communication model based on SIP and ZigBee for intelligent home electricity system

In order to use the electricity resources even more intelligent, efficient and safer, the concept of intelligent home electricity system was presented. Based on the analysis of the requirement of the intelligent home electricity system, the Home Gateway and SPO (Smart Power Outlet) were designed to integrate the isolated WSN (Wireless Sensor Network) and the Internet to achieve communication between different networks. The communication model based on SIP/ZigBee which is the combination of the core protocol of NGN (Next Generation Networks) and the technical characteristics of the main communication technology of the WSN was created. SIP extension and two kinds of control algorithms were put forword. The selection of the communication model based on SIP and ZigBee is the first step towards an intelligent home residence.

CMT-SR

Conversational video service is characterized by the high bandwidth demand, and the stringent and low delay requirement. High-quality delivery service for conversational video service not only depends on end-to-end bandwidth but also relies on control mechanisms to alleviate the impact of packet loss on video quality. Multipath transmission is considered to be a promising solution to expand end-to-end bandwidth. However, existing multipath transmission schemes are not suitable for conversational video service delivery because they incur either a large number of duplicated packet or a large delay. In this work, retransmission mechanism that satisfies delay requirement is discussed to recover packet loss. The main problem of the retransmission mechanism is the delay. A selective retransmission based concurrent multipath transmission mechanism (CMT-SR) is proposed to optimize the performance of retransmission. Several mechanisms are adopted to retransmit the lost packet in an optimal way. CMT-SR monitors and analyzes the bandwidth and delay of each path, which provides a foundation for estimating arrival time of data packet. Push-based and pull-based mechanisms support sender to be aware of packet loss timely. CMT-SR differentiates between different frames of packet loss. Finally, CMT-SR first retransmits the key parts of the video data over an alternative path considering the decoding deadline, retransmission delay, and characteristic of video streaming. CMT-SR is a reliable multipath transmission scheme for conversational video service and is evaluated by extensive simulations and actual tests. Experimental results show that CMT-SR is an effective way to improve the quality of conversational video service delivery.

A multipath transport system based on application level relay

Multipath transport is an important way to improve the transmission performance of Internet applications. This demo presents a multipath transport system based on application level relay (MPTS-AR), which defines three kinds of logical entity of user agent, controller and relay server. Controller and relay server collaboratively provide relay services, and user agent integrates the multipath transmission control mechanism and protocol stack. It also defines a relay service control protocol named OpenPath in control plane and a suite of multipath transport protocols (MPTPs) in data plane. The example of SIP-based real-time audio media session further illustrates the practicability of MPTS-AR.

A multipath relay transport control method for real-time video service

Multipath relay transport system supports end-to-end media multipath transmission through relay controller and relay server. The performance of multipath transport not only depends on path quality, but also depends on end-to-end multipath transport control mechanism and protocol. Analyzing the features of real-time video service and requirement of multipath transport control, this work proposes a model to evaluate the quality of service (QoS) weight of path. It designs a load distribution algorithm based on the features of service and the QoS weight. It also designs a subflow reassembling algorithm based on dynamic receiver buffer. Finally, OMNeT++ simulations were conducted to verify the rationality and feasibility of the model and algorithm.