Tsunehiko Chiba

Efficient Route Optimization Methods for Femtocell-Based All IP Networks

Recently, femtocells, which cover a cell area of several tens of meters, have been attracting considerable attention in mobile communications. When a femtocell is connected through a public network, such as a broadband access network or the Internet, a secure tunnel is established between the femtocell and the security gateway located in the mobile core network and media data are sent and received over that tunnel. Therefore, if the security gateway is far away from the femtocells and those femtocells are in close proximity with each other, the routing path of the media data between users becomes redundant. Moreover, the intensive processing due to encryption and decryption for the media data protection could impact on the load of the security gateway. In this paper, we propose efficient media path optimization mechanisms by sending and receiving media data directly between femtocells in coordination with IMS (IP Multimedia Subsystem), which is expected to be a core technology for session control in an all-IP network, and evaluate the proposed mechanisms using a commercial femtocell.

Self organizing IP Multimedia Subsystem

While there have been tremendous efforts to develop the architecture and protocols to support advanced Internet-based services over 3G and 4G networks, IMS is far from being deployed in a wide scale manner. Effort to create an operator controlled signaling infrastructure using IP-based protocols has resulted in a large number of functional components and interactions between those components. Thus, the carriers are trying to explore alternative ways to deploy IMS that will allow them to manage their network in a cost effective manner while offering the value-added services. One of such approaches is self organization of IMS. The self organizing IMS can enable the IMS functional components and corresponding nodes to adapt them dynamically based on the features like network load, number of users and available system resources. This paper introduces such a self organizing and adaptive IMS architecture, describes the advanced functions and demonstrates the initial results from the prototype test-bed. In particular, we show how all IMS functional components can be merged and split among different nodes as the network demand and environment change without disrupting the ongoing sessions or calls. Although it is too early to conclude the effectiveness of self organizing IMS, initial results are encouraging and it may provide additional incentives to the operators for network evolution.

Performance Analysis of Next Generation Mobility Protocols for IMS/MMD Networks

In an effort to provide seamless mobility support in IMS/MMD networks, operators need to choose a specific IP- based mobility protocol. However, there are several micro- and macro-mobility protocols available that the operators can choose from. Operators often face the challenges of selecting the appropriate mobility protocol that can provide the most cost efficient solution under a specific operating environment. Thus, it is important to analyze the effectiveness of these protocols before they are actually deployed in the IMS/MMD networks. In this paper, we analyze a number of candidate mobility protocols and conduct a performance analysis of some of these using a prototype implementation in an IPv6-based IMS/MMD testbed. These analyses provide us with some guidelines in terms of the applicability of these protocols when operators plan to deploy their IMS/MMD networks.

Mobility Management Schemes for Heterogeneity Support in Next Generation Wireless Networks

Seamless mobility support in a heterogeneous roaming environment poses several challenging issues in the choice of network architecture design and mobility protocol. Several standards organizations are designing next generation wireless network architectures with a suite of new network elements and protocols that provide service continuity for intra-and inter-provider roaming. However, each of these mobility solutions provides its own set of signaling mechanisms and methods of interaction with different functional network elements. Thus, it becomes a challenging task for the network operators and service providers to support roaming to the visited networks with diverse capabilities while supporting service continuity. In this paper, we first highlight some of the next generation standards and then describe the main functional components of a generic next generation wireless architecture as described in several evolving standards. We then focus on the operational usage of network layer mobility protocols such as Client Mobile IP, Proxy Mobile IP and application layer mobility protocol for next generation networks, and address the operational issues associated with roaming and service continuity. Finally, we propose comprehensive mobility solutions that support the heterogeneity associated with the intra-and inter-provider roaming.

Route optimization for Proxy Mobile IPv6 in IMS network

Localized mobility protocols are designed to address many of the drawbacks such as additional signaling and over-the-air tunnel overhead associated with global mobility protocols like Mobile IPv4 and Mobile IPv6. Proxy Mobile IPv6 is one such network controlled localized protocol defined in the IETF Although Proxy Mobile IPv6 can resolve longer binding update and tunnel overhead related issues when a mobile nodes movement is confined to a specific domain, some of the handoff-related functions and data paths between two communicating nodes still need to be optimized. The data path reduction between the communicating nodes helps to reduce one way packet delay when both nodes are under the same localized domain and the local mobility anchor point is away. The process of reducing the data path is often referred to as route optimization. Route optimization helps to reduce the delay due to media delivery that is critical for real-time application. We propose several route optimization techniques that can be applied to Proxy Mobile IPv6 to improve the efficiency of media delivery for both intra- and inter-domain movements. We select one of these proposed route optimization mechanisms and then describe the implementation details and analyze the experimental results.

A-IMS architecture analysis and experimental IPv6 testbed

Advances to IMS (A-IMS) architecture extends the existing IMS/MMD architecture currently being defined in 3GPP/3GPP2 respectively so that it can support both SIP and non-SIP-based services. We describe the key strength of A-IMS architecture, compare the benefits over MMD architecture, and then describe an enhanced MMD experimental testbed to demonstrate many of the A-IMS features. We highlight many of the functional components of the testbed that perform several operations such as signaling, location management, security, and mobility. We experiment with two different mobility management techniques and analyze the associated delays and packet loss for both 802.11 networks and PPP networks. We illustrate the service interaction between SIP-based services such as VoIP and non-SIP-based services such as IPTV. Analysis from these experimental results and testbed implementation can be useful to any service provider that plans to deploy IMS/MMD architecture over IPv6.

Trombone Routing Mitigation Techniques for IMS/MMD Networks

Real-time services such as VoIP and multimedia streaming are affected during a mobiles rapid handoff due to the associated delay resulting from associated handoff operations of discovery, detection, configuration, registration, media redirection, and processing at different network nodes. Redundant communication path of any signaling and media adds to the delay during session setup and media delivery. This paper highlights the overall problem associated with redundant routing in a 3GPP2-based MMD (multimedia domain) environment and proposes several mechanisms to mitigate these problems. We also compare these mechanisms and select one for existing IMS/MMD networks that use MIPv4 as the mobility protocol. We present the implementation details of the selected redundant routing mitigation technique in the experimental MMD environment and verify the effectiveness by analyzing the measurement results.

Generalized Modeling Framework for Handoff Analysis

A mobility event is the result of one network connection path being replaced by another via the rebinding of common system properties. The rebinding is a sequential process that may potentially involve multiple protocol layers of the mobile and require multiple network interactions. This overall process results in a period of time in which network service is degraded by transient data loss and increased end-to-end delay. Optimizations of the handover process mitigating these service degradations have been developed without a formal or systematic framework for mobility solutions. We develop a systematic systems model of the basic properties associated with a mobility event and design a framework around these properties that can provide methodologies for optimizing the handoff components. We then summarize the experimental results from a 3GPP2-based mobility testbed and highlight the delays associated with the functional components of the handoff event. We apply two types of optimization techniques and compare the results.

Gap Analysis and Deployment Architectures for 3GPP2 MMD Networks

Mobile and fixed operators are offering broadband access to the Internet by either adding wireless access to their existing core networks (e.g., CDMA IxEVDO. GPRS, and WiFi) or continuing to evolve existing broadband infrastructures (e.g., DSL, Cable and FTTx). Consequently, IMS and MMD architectures as defined by 3GPP and 3GPP2 are becoming increasingly important to network operators, in particular, for offering ubiquitous service and seamless mobility to end users, along with management and control Although 3GPP2 MMD architecture has adopted most of the 3GPP IMS core functionalities and interfaces, it added several other unique functional components and interfaces to fit the specific need of CDMA2000 access networks Therefore, it is important to understand the gaps and issues associated with the 3GPP2 MMD architecture with regard to the 3GPP IMS architecture. In this paper, we first analyze the functional and protocol level differences between IMS and MMD architectures. Based on our analysis, we then articulate several deployment architectural alternatives for 3GPP2 MMD networks and finally analyze the pros and cons of each architecture.

Enhanced Next-Generation Service Overlay Networks architecture

The Web Services composition paradigm has been widely used in Information Technology (IT) and Internet environments to create Web applications that both flexible and rapidly deployable. Web Services are a key way to realize Service-Oriented Architectures (SOA). In Telecom, on the other hand, the IMS (IP Multimedia Subsystem) architecture enables valued-added services composition for IP-based networks. Several ongoing efforts - referred to as “SOA for telecom” (SOA-TEL) - are attempting to merge SOA with telecom. The objective of these attempts is to enable Telecom operators and service providers to re-use existing service building blocks while building valued-added converged Web and telephony services. These services offer seamless experiences across various networks and, therefore, richer experiences, but are more complex than typical Web Services (e.g., transaction-based). The IEEE Next-Generation Service Overlay Networks (NGSON) working group is focusing on this integration and an architecture has been proposed. In addition, NGSON specifies context-aware, dynamically adaptive, and self-organizing networking capabilities. There are, however, a number of shortcomings in the NGSON architecture. This paper identifies these shortcomings and describes a possible solution. Finally, we discuss an illustrative use case scenario to help bring clarity to our proposed “enhanced” NSGON architecture.