Christophoros Christophorou

MBMS Handover control: A new approach for efficient handover in MBMS enabled 3G cellular networks

With the introduction of Multimedia Broadcast Multicast Service (MBMS) system in 3rd Generation (3G) mobile cellular networks, the Radio Network Controller (RNC) for radio resource efficiency can use either Point-to-Point (one Dedicated Channel per User Equipment (UE) in the Cell) or Point-to-Multipoint (one Common Channel shared by all the UEs in the Cell) transmission mode, to distribute the same MBMS content in a Cell. Thus, the mobile users that are on the move and receive an MBMS service may have to deal with dynamic changes of network resources when crossing the Cells edge, introducing new types of handovers (MBMS Handovers); from Point-to-Point to Point-to-Multipoint transmission mode Cell and vice versa. Executing an MBMS Handover using the existing handover control approach, as described in 3GPP TR 25.922 specifications, results in inefficiencies due to the approach used. In this paper, we highlight these inefficiencies and propose and evaluate a new handover control approach to address them. As illustrated in our performance evaluation, compared to the existing approach, the proposed approach improves the overall system capacity and link performance and avoids any QoS degradation (seamless handover) during an MBMS Handover.

Context-aware control for personalized multiparty sessions in mobile multihomed systems

Telecommunication and Internet services are constantly subject to changes, seeking customers satisfaction. Enriching services with innovative approaches such as context-aware, mobile, adaptable and interactive mechanisms, enables users to experience personalized services seamlessly across different technologies. Aiming at evolving mobile multimedia multicasting to exploit the increasing integration of mobile devices with our everyday physical world, a context-aware multiparty delivery needs to research into two important frameworks: context detection and distribution and context-aware multiparty networking, encompassing adaptations at the session, transport, and network layers. The paper diverges into the second by focusing on the user perceived Quality of Experience and efficient network support of real-time group communications, allowing dynamic adaptation of the multiparty delivery, group communications optimization and maximization of group members overall satisfaction.

An Efficient Handover Algorithm for MBMS Enabled 3G Mobile Cellular Networks

With the introduction of Multimedia Broadcast Multicast Service (MBMS) in 3rd Generation (3G) Networks, the Radio Network Controller (RNC) for radio efficiency reasons can use either Dedicated or Common resources to distribute the same content in a Cell. Thus the mobile users that are on the move may have to deal with dynamic changes of network resources when crossing the cell edge, introducing new types of handovers (MBMS Handovers). Executing an MBMS Handover using the current Handover Algorithm will result in inefficiencies. Therefore, for efficient execution of these new types of handover a different approach has to be followed. This paper proposes a new Handover Algorithm which efficiently maximizes the overall system capacity when mobile MBMS users have to deal with these new types of handovers.

Architecture for context-aware multiparty delivery in mobile heterogeneous networks

Future networks are envisioned to satisfy the user needs and improve their quality of experience. This requires the networks to support context-aware information, where context of the user, session, network and environment will greatly influence the way the session is delivered: new approaches are required to deal with the overall context information and network reaction to constantly context changes. This paper presents a context-aware architecture that provides delivery of multiparty services in heterogeneous and mobile environments. The architecture, its elements and functionalities are described through a specific application to a context-driven use case scenario. We show that this architecture is able to provide personalized and multiparty services to the users, addressing their characteristics and preferences, and optimizing network support while mobility and heterogeneous environments are in place.

An enhanced approach for efficient MBMS handovers in 3G networks

With MBMS, a mobile terminal (MT) that is on the move and receive an MBMS service may have to handover from a common to a dedicated channel when crossing the cellpsilas edge. In previous work, we highlighted the possible inefficiencies which might arise if the existing 3GPP handover control approach is adopted to execute these types of handovers and proposed a specific MBMS handover control approach that compensated for them. This approach, although effective in terms of capacity and QoS, was not very viable. Thus in this paper, using a different approach, we enhance previous work in order to address its deficiencies and make the whole solution practical. The performance evaluation showed that our enhanced proposed approach even with the enhancements made simplifying the whole handover procedure, still outperforms the existing 3GPP handover control approach in terms of capacity and QoS efficiency.

Power counting for optimized capacity in MBMS enabled UTRAN

MBMS bearer services can be provided in each cell by either point-to-point or point-to-multipoint transmission mode but for efficiency a decision has to be made between the two approaches. Initially, the fundamental criterion used to make this decision was the number of MBMS users in a cell (UE counting). In this paper we extend our previous work, which proposed the power transmitted by the base station (BS) as the channel switching criterion (power counting). We evaluate our approach and illustrate its capability to dynamically adapt to continuously varying cell conditions by selecting the transmission mode in a more efficient way, preserving in this way the networkpsilas resources. At the same time we demonstrate the limitations of the conventional approach, in terms of radio resource efficiency. We show that by having the power used by the BS as the limiting factor we achieve optimized capacity during the transmission of MBMS bearer services in UTRAN.

Context-Aware Self-optimization in Multiparty Converged Mobile Environments

The increase of networking complexity requires the design of new performance optimization schemes for delivering different types of sessions to users under different conditions. In this scope, special attention is given to multi-homed environments, where mobile devices cross areas with overlapping access technologies (Wi-Fi, 3G, WiMax). In such scenario, efficient multiparty delivery depends upon the grouping operation (creation of a set of users to receive a given session), which must be done based on several parameters. We propose sub-grouping of content-based service groups, so that the same service session can be delivered using different codings of the same content, to adapt to the current network, users, session and environment context. The context-aware information is used to improve the sub-grouping process. This paper aims to describe these sub-grouping techniques, in particular how they improve network performance and user experience in the future Internet, in the scope of cognitive autonomic networks.

A new approach for efficient MBMS service provision in UTRAN

As currently specified by 3GPP, MBMS services can be provided in a cell either by point-to-point (PtP) or point-to-multipoint (PtM) transmission mode, but not both at the same time. With PtP transmission mode, one dedicated channel (DCH) is established for each MBMS user within the cell. With PtM transmission mode one forward access channel (FACH) is established, covering the whole cellpsilas area and commonly shared by all the MBMS users within. In this paper we describe the existing 3GPP MBMS service provision approach, highlight its deficiencies, and propose a new approach to address them. To achieve this we introduce the ldquodual transmission mode cellsrdquo in which PtP and PtM transmissions can coexist and where FACHpsilas coverage range can be dynamically adapted (shrink or expand) through time based on the MBMS userspsila location within the cell. The performance evaluation performed, showed that our approach outperforms the existing 3GPP approach in terms of capacity, signaling and processing effort efficiency.

Session and Network Support for Autonomous Context-Aware Multiparty Communications in Heterogeneous Mobile Systems

The increase of networking complexity requires the design of new performance optimization schemes for delivering different types of sessions to users under different conditions. In this regard, special attention is given to multi-homed environments, where mobile devices cross areas with overlapping access technologies Wi-Fi, 3G, WiMax. In such a scenario, efficient multiparty delivery depends upon the grouping operation, which must be done based on several parameters. In this paper, the authors propose context-aware sub-grouping of content-based service groups so that the same service session can be delivered using different codings of the same content, adapting to current network, users, session, and environment context. The context-aware information is used to improve the sub-grouping process. This paper aims to describe these sub-grouping techniques, and in particular how they improve network performance and user experience in the future Internet by focusing on the improved network-level and session-level mechanisms.

MBMS Handover Control for Efficient Multicasting in IP-Based 3G Mobile Networks

Handover Control in a cellular infrastructure aims to provide continuity of mobile services to a user traveling over cell boundaries. So far, Handover Control is considered only between cells supporting the service using Dedicated Resources and the handover decision making is based on a comparison between an observed signal strength value and a predetermined threshold chosen in a manner so as to maximize the overall system capacity. With the introduction of Multimedia Broadcast Multicast Service (MBMS), for radio efficiency reasons, one cell can use either Common or Dedicated resources for the distribution of the same content in a Cell. Thus, the mobile users that are on the move may have to deal with dynamic changes of network resources when crossing the cell edge, introducing new types of handovers (MBMS Handovers). Using the current Handover Algorithm when an MBMS Handover is executing will not be so efficient. For the efficient execution of these new types of handover a different approach has to be followed. This paper proposes a new Handover Algorithm which efficiently maximizes the overall system capacity when mobile MBMS users have to deal with these new types of handovers.