Khong Neng Choong

RSSI-based location tracking method for device switching of real-time application

Wireless technology offers flexibility and mobility that enables users to access to any service including voice call, anytime, anywhere with any device. Transferring call or session across devices is also made possible with todays session management protocol such as SIP, provided the user knows the contact information of the target device. In this paper, we propose a method which simplifies the transfer of session across devices whereby the target device is automatically selected based on its proximity to the active source device. Such automation is enabled with the use of a customised Location Server that performs location estimation of all registered devices using the RSSI-based triangulation method. Our proposed method successfully eliminated the error-prone manual intervention on the selection of target device during the transfer, and achieved a small average error of 0.21 meter.

Cross-domain data exchanges for web application

Today, most modern web applications contain the combination of information and presentation from more than one server in order to make the web application more interesting and delivering acceptable performance. Thus, Cross-Domain communication is used to enable those servers to communicate and exchanging data to each other. In this paper, a survey has been made on some available techniques of Cross-Domain communication in order to be applied in a specific system, which is a real time web application system. The techniques included were chosen based on the current practice of most developers. A signalling based experiment on newly emerged techniques - post Message and CORS, besides Browser Plugin technique was also conducted. All these techniques have been compared to each other to identify the suitability of the techniques in order to be implemented in real time web application based on these requirements; functionalities separation, process invisibility, and data size independent. (6 pages)

Performance Study on Location-Assisted and Bluetooth-Assisted Session Transfer for VoIP Application

With the increasing use of small, lightweight, powerful and multi-radio devices, and the omnipresence of wireless networks such as WiFi, the pave to ubiquitous computing is gradually emerged and realized. Ubiquitous computing allows users to access their services using any device, anytime, anywhere in a very flexible manner based on the current context. In particularly, services could be started on one device that attaches to one network and later be easily switched to another device connected to another network, commonly known as session mobility. In this paper, we describe our concept of seamless session transfer for real-time application such as VoIP and IPTV, and our prototype implementation of such concept using both WiFi and Bluetooth approaches, with qualitative and quantitative performance comparison.

Seamless handover between unicast and multicast multimedia streams

With the deployment of heterogeneous networks, mobile users are expecting ubiquitous connectivity when using applications. For bandwidth-intensive applications such as Internet Protocol Television (IPTV), multimedia contents are typically transmitted using a multicast delivery method due to its bandwidth efficiency. However, not all networks support multicasting. Multicasting alone could lead to service disruption when the users move from a multicast-capable network to a non-multicast network. In this paper, we propose a handover scheme called application layer seamless switching (ALSS) to provide smooth real-time multimedia delivery across unicast and multicast networks. ALSS adopts a soft handover to achieve seamless playback during the handover period. A real-time streaming testbed is implemented to investigate the overall handover performance, especially the overlapping period where both network interfaces are receiving audio and video packets. Both the quality of service (QoS) and objective-mapped quality of experience (QoE) metrics are measured. Experimental results show that the overlapping period takes a minimum of 56 and 4 ms for multicast-to-unicast (M2U) and unicast-to-multicast (U2M) handover, respectively. The measured peak signal-to-noise ratio (PSNR) confirms that the frame-by-frame quality of the streamed video during the handover is at least 33 dB, which is categorized as good based on ITU-T recommendations. The estimated mean opinion score (MOS) in terms of video playback smoothness is also at a satisfactory level.

Session Switching between IP/PSTN Connectivity for Voice Application

Session switching or session transfer across devices has become a common feature in todays telecommunication world, given that a single user could easily own more than one device. However, most of the systems in the literature are designed for homogeneous network, i.e. switching session within a common network such as across only IP devices. In this paper, we design a prototype to support session switching across devices in different network, which is from IP to Public Switch Telephone Network (PSTN) and vice versa. Our prototype is built on top of an IP Multimedia Subsystem (IMS) to leverage on its standard convergence interface with media gateway. Experimental results shown that our session transfer took an extra of 0.31 second more than the IP-to-IP session switching.

Prototype implementation of a connection handover system for video streaming with different delivery methods

With the emergence of multimode terminals and the deployment of multiple access networks, users are expecting ubiquitous and seamless connectivity across heterogeneous networks when using IP-based applications. For bandwidth intensive IP-based application such as Internet Protocol Television (IPTV), the multimedia contents are usually transmitted via multicast delivery for reason of efficiency. However, not all networks support multicast. Hence, multicast video delivery could lead to service disruption when users move from a network with multicast support to another network that is not. In this paper, we propose a system called Application Layer Switching System (ALSS) that focuses on switching video transmission between multicast and unicast delivery methods. More specifically, we study the overlapping period needed by the mobile terminal to achieve smooth video playback for different videos during connection handover.

The triggering mechanism of mobile server allocation for video live-casting application

The growth of real-time video traffic on the Internet requires high bandwidth which causes the use of the conventional point-to-point method to deliver the video is not relevant anymore. Content providers are now leveraging the Content Delivery Network (CDN) and Peer to Peer Network (P2P) to reduce the inter-ISP traffic thus improving the end user experience. On the other hand, the Dynamic Mobile Server (DMS) approach has been proposed where a server is dynamically allocated in the Local Area Network to confine the traffic in the local network. In this paper, the triggering of server allocation and the client redirection of DMS have been analysed. The experimental results showed that the server allocation takes under 37 seconds to complete while the client redirection could be done in less than one second in the network with more than 90% of the bandwidth has been utilized.

Real-time application Session Transfer over IP Multimedia Subsystem (IMS) Network

Living in a world surrounded by multiple devices such as smart phone, laptop, desktop PC and even tablet, it is important for the user to seamlessly transfer his/her session across these devices in a ubiquitous manner according to user preferences. While most of the systems either rely on realtime location tracking of the target device, or require users to remember the contact or IP address of the target device for the transfer, we propose in this paper an automated session transfer mechanism leveraging on the registration information which are readily found in the IP Multimedia Subsystem (IMS) core. We explain in this paper the system architecture and signaling flow of our prototype implementation. Results showed that our proposed mechanism for session transfer over both wired and wireless access network took 202ms and 388ms respectively, which stays within the ITU-T recommendation of 150ms to 400ms overall delay. (4 pages)

Bridging digital divide in Malaysia using low cost WiMAX-WiFi multi-hop network

An integrated multi-tier, multi-hop WiMAX-WiFi network is seen as a promising solution to provide fast and low cost broadband access to places where the wired infrastructure is not ready or is too expensive. This paper investigates the potentials of deploying such network in rural Malaysia. The role of IEEE802.16 (WiMAX) WMAN technology is basically to provide backhaul support i.e. carry traffic from various access nodes to the gateway and hence the Internet, while the IEEE802.11 WLAN (WiFi) provides access service to the end users. This paper provides some insights on the capacity and coverage and performance of the proposed architecture. Its capability to provide multimedia services is also investigated using a representative village scenario in Malaysia. (6 pages)

Prototype implementation of a presence-based multimedia session sharing system

Emailing has been and it is still continue to be the most common way for many people to share information using texts and/or with attachments. More popular alternatives nowadays are using the Instant Messengers (IM) and online community networks which convey presence information and provide higher degree of interactions with richer multimedia experience. However, these existing systems involve human intervention onto updating the status information, e.g. the presence status message is manually entered and remains unchanged until the next manual update. A more sophisticated presence system would be those which can determine a users status automatically, with the objective to enable more interactions including indirect contents sharing. In this paper, we present the prototype implementation of a presence-based multimedia session sharing system. This proposed system helps users to publish their session dynamically, and enable their buddies/contacts to join the same session as to consume the contents. We envisaged that the proposed system would help service providers to advertise and promote their contents at lower cost with a viral effect.