Jun Kyun Choi

Adaptive Hybrid Transmission Mechanism for On-Demand Mobile IPTV Over WiMAX

In this paper, we propose an Adaptive Hybrid Transmission (AHT) scheme for on-demand mobile IPTV service over broadband wireless access network (i.e. mobile WiMAX, 802.16e). Proposed algorithm utilizes hybrid mechanism which combines multi-channel multicasting and unicast scheme to enhance not only service blocking probability but also reduce overall bandwidth consumption of the wireless system which has very limited resources compared to wired networks. An adaptive resource allocation algorithm is also proposed, and is shown to achieve minimum blocking probability. In order to evaluate the performance, we compare proposed algorithm against traditional unicast and multicast schemes.

Energy Efficient Cooperative Multicast Scheme Based on Selective Relay

Multicast communication has been researched for many years in efforts to simultaneously achieve high throughput and good fairness, which have a trade-off relationship. Recently, a cooperative multicast scheduling scheme was proposed. It is considered a promising solution owing to its trade-off characteristics realized by promoting user cooperation among group members. However, it requires significant relay power consumption for user cooperation, since all group members in a good channel condition should relay without checking whether there is at least one user requesting a relay in the transmission boundary. Therefore, in order to resolve this inefficiency, we proposed an energy efficient cooperative multicast scheme (EECM) based on selective relay. We can achieve reduced unnecessary relay power expenditure by selecting relay users with consideration of the condition of nearby users. The performance results derived from a numerical analysis reveal that the proposed scheme requires less energy consumption than the existing solution with almost the same throughput performance.

Performance evaluation of an optical hybrid switching system

We propose a new optical hybrid switching system that takes advantage of both optical burst switching (OBS) and optical circuit switching (OCS) technologies. This system classifies incoming IP traffic flows into short-lived and long-lived flows. We model the system as a single server queue in a Markovian environment. The burst generation process is assumed to follow a two-state Markov modulated Poisson process (MMPP), and the service rate fluctuates based on the number of concurrent OCS sessions. Results for the mean delay and queue size are derived.

Adaptive Delay-Aware Energy Efficient TDM-PON

Passive Optical Networks (PONs) are widely adopted as the last-mile technology due to the large bandwidth capacity it provides to end users. In addition, PON is viewed as a green access technology since it reduces energy consumption compared to other access technologies (e.g. Fiber to the Node). However, there is still room for enhancing the energy efficiency of PON further, and we can find many attempts along those lines in academia and industry. A widely used approach to save energy in Time Division Multiplexing (TDM)-PON is to keep the Optical Network Units (ONUs) in sleep mode when they do not have anything to receive or transmit. However, sleep intervals have a direct negative impact on increasing traffic delay. Therefore, energy efficiency in a TDM-PON presents a clear trade-off: the longer an ONU sleeps, the less energy it consumes, but the higher the delay experienced by the downlink traffic, and vice versa. In this paper, we propose an Adaptive Delay-Aware Energy Efficient (ADAEE) TDM-PON solution. The ADAEE aims at saving as much energy as possible while meeting the PON access delay restrictions imposed by the operator. We evaluate our solution in terms of energy consumption and delay performance using real traffic traces. The results demonstrate that the proposed solution can meet delay requirements while being more energy efficient solution compared to the existing solutions.

Functional Architecture for NGN-Based Personalized IPTV Services

IPTV is one of the most highly visible services to emerge as part of the development of next generation network (NGN). IPTV services over manageable broadband link from a provider will be one of the ultimate goals of the broadband revolution using NGN. In this paper, we analyze IPTV architecture developed by ITU-T and provide functional architecture for NGN-based IPTV services according to functional mapping between IPTV and NGN. For this, we provide the detailed functional architecture and relevant operations with other functional blocks and present the harmonized architecture between IPTV and NGN for NGN-based IPTV services with the alignment with existing NGN architecture. As challenging architectural issues, we also introduce personalized IPTV services based on Web-based open platform in NGN environment and illustrate functional architecture and service examples for Web-based personalized IPTV services.

A handover framework for seamless service support between wired and wireless networks

This paper proposes low latency handover procedure for seamless connectivity and QoS support between wired (e.g. Ethernet) and wireless (e.g. WLAN, WiBro (802.16-compatible), CDMA) networks by the mobile-assisted and server-initiated handover strategy. It is assumed that the server decides the best target network considering network status and user preferences. In this procedure, a mobile terminal associates with the wireless link decided at the server in advance and receives CoA as well. When handover occurs without the prediction in wired networks, the server performs fast binding update using physical handover trigger through the MIH (media independent handover) function. As a result, a mobile terminal does not need to perform L2 and L3 handover during handover so that this procedure decreases handover latency and loss

QoS negotiation for IPTV service using SIP

This paper addresses QoS negotiation algorithm for IPTV services by using SIP. IPTV is defined as multimedia services such as television/video/audio/text/graphics/data delivered over IP based networks managed to provide the required level of QoS/QoE, security, interactivity and reliability by the ITU-T IPTV FG. As stated in its definition, IPTV provides the required level of QoS/QoE. To achieve this, IPTV service frameworks should be able to negotiate QoS/QoE with users or customers and SIP is one of the most proper methods for the SLA negotiation.

A study on path re-routing algorithms at the MPLS-based hierarchical mobile IP network

This paper proposes the multiprotocol label switching (MPLS)-based hierarchical Mobile IP architecture to allow frequent and seamless location management It proposes that the label distribution protocol (LDP) can be applied to set up the label switched path (LSP) tunnels between the mobile agents (that is, foreign agents and home agents). It means that the IP-in-IP tunnels can be replaced by one or multiple LSP on the MPLS network. When a mobile node (MN) migrates to the adjacent subnet, it performs a regional registration and partial LSP re-establishment method. So our scheme can reduce LSP setup latency more than the existing integration of Mobile IP and MPLS. We also propose a multicast re-routing scheme to support smooth handover on the MPLS-based hierarchical Mobile IP network after analyzing several LSP re-routing schemes.

Evaluating Energy Efficiency of ONUs Having Multiple Power Levels in TDM-PONs

A TDM Passive Optical Network (TDM-PON) proposes the use of sleep modes for Optical Network Units (ONUs) to maximize Energy Efficiency (EE). When an ONU manages a sleep mode, it needs to turn on and off some of its components based on communication requirements. Hence, an ONU ends up with multiple power levels. Existing analytical models for evaluating EE consider that an ONU has only two power levels. However, we have found in some literature where an ONU can have more than two power levels. In this letter we propose an analytical model to quantify the EE of an ONU having more than two power levels. We demonstrate the accuracy of the model by means of simulation under two different sleep interval deciding algorithms.

Energy Efficient Scalable Video Coding Based Cooperative Multicast Scheme with Selective Layer Forwarding

Scalable Video Coding (SVC) based multicast schemes have been researched for many years in efforts to simultaneously achieve high throughput and good fairness, which have a trade-off relationship in multicast communication. In an SVC based multicast, all group members in a good channel condition can receive both base layer and enhancement layer information and thus can recover high quality video, while other group members receive the base layer information for guaranteeing basic quality video. However, this causes differentiation of video quality between group members with varying channel conditions, and average video quality is consequently degraded. We propose an Energy Efficient SVC based cooperative multicast (EE-SVC-CM) scheme with selective layer forwarding as a novel approach to mitigate this problem. The performance results reveal that the proposed scheme enhances the overall energy efficiency (throughput per watt) with reduced unnecessary relay power consumption.