FIELD OF INVENTION

The present invention relates to a method for performing real time seamless Internet Protocol (IP) multicast connection handoff.

BACKGROUND ART

With the increase in usage of Internet Protocol (IP) based applications, such as IPTV on mobile devices, there is a need for seamless mobility multicast connection handoff to entirely remove or to minimize interruption during mobile sessions of the IP based applications. Seamless mobility multicast connection handoff of the IP based applications, such as IPTV, requires mobility management that allows a mobile device to move between different network types, either fixed or mobile network type, and continually receive data from a source, for instance receiving IPTV contents from a remote IPTV server.

Several mobility management protocols and solutions have been proposed to address the issue of mobility. These protocols and solutions are transparent to a user and have the object of minimizing interruption during mobile sessions. Mobile IP (MIP) is one of the many mobility management protocols that performs mobility handoff that is transparent to the user, wherein there is no change of IP address throughout the entire session. However, the implementation of this protocol in multimedia traffic such as IPTV traffic, which is delay-sensitive, is not efficient as all traffic must flow through a home agent back to the mobile device connected to a foreign agent. Furthermore, MIP being at the IP layer has no knowledge of the type of application applied at the application layer, hence is unable to address the requirements and contexts of the application in an optimal manner.

Additionally, MIP protocol requires an IP mobility infrastructure that includes a home agent and foreign agent, to be available. Implementing mobility management protocol at the application level imposes less infrastructure requirements. For instance, the implementation of Session Initiation Protocol (SIP) avoids modifying the IP layer protocol stack in the mobile device, which results in uncomplicated installation and deployment.

To provide for seamless mobility multicast connection handoff during mobile sessions of the IP based applications, such as IPTV ₁ besides being transparent to the user, packet lost and delay must be minimized as noticeable interruption will degrade user experience during the mobile sessions.

Prior art WO 2007/130012 A1 , describes a method to recover multicast session from lost packet during the connection handoff. This is achieved by generating a delayed data packet alongside the original data packet (also known as staggercasting) serving as backup stream. Another alternative embodiment is to staggercast a lower bit rate version of the original data or staggercast parity data generated by a cross-packet forward error correction code.

In another prior art, US 6993000 B2, a method for selecting IP data packet segments in an all-IP architecture that support handoff via IP multicasting is described. A best IP data packet is selected from a plurality of similar data packets (from each surrounding base stations) based on three basic variables, that are number of base stations, number of time segments in a single IP data packets and number of quality metrics.

However, there is a need for seamless mobility multicast connection handoff between different network types, that may be different combinations of both fixed and mobile network types, wherein mobility multicast connection handoff from one network type to another may be performed transparently with the user experiencing minimal or no degradation during the mobile sessions.

SUMMARY OF INVENTION

In one embodiment of the present invention is a method for real time seamless Internet Protocol (IP) multicast handoff from a network interface of a current network to a network interface of a new network. The method comprises activating the network interface of the new network, determining a delay duration for seamless Internet Protocol (IP) multicast handoff, receiving a plurality of Internet Protocol (IP) packets on the network interface of the new network and de-activating the network interface of the current network upon expiration of the delay duration.

The present invention consists of several features and a combination of parts hereinafter fully described and illustrated in the accompanying drawings, it being understood that various changes in the details may be made without departing from the scope of the invention or sacrificing any of the advantages of the present invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

To further clarify various aspects of some embodiments of the present invention, a more particular description of the invention will be rendered by references to specific embodiments thereof, which are illustrated, in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the accompanying drawings in which:

FIG. 1 illustrates a flowchart of a method for real time seamless Internet Protocol (IP) multicast connection handoff.

FIG. 2 illustrates a detailed flowchart of a method for real time seamless Internet Protocol (IP) multicast connection handoff.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a method for real time seamless Internet Protocol (IP) multicast connection handoff. Hereinafter, this specification will describe the present invention according to the preferred embodiments of the present invention. However, it is to be understood that limiting the description to the preferred embodiments of the invention is merely to facilitate discussion of the present invention and it is envisioned that those skilled in the art may devise various modifications and equivalents without departing from the scope of the appended claims.

The present invention adopts an application level approach for real time seamless Internet Protocol (IP) multicast connection handoff from one network to another, either fixed or mobile network, that is transparent to a user and is independent of any mobility protocol such as Mobile IP (MIP) or Session Initiation Protocol (SIP), and hence free from and not bounded to any specific network infrastructure.

The real time seamless IP multicast connection handoff of the present invention resides in the management of network interfaces of a mobile device or mobile node. The said management includes activating and receiving sufficient IP packets or data packets on a new interface before de-activating a current interface of the mobile node. Unlike MIP and SIP, the real time seamless IP multicast connection handoff of the present invention does not generate signaling messages except for dynamically subscribing and unsubscribing to a particular multicast group.

Reference is collectively being made to FIGs. 1 and 2. FIG. 1 illustrates a flowchart of a method for real time seamless IP multicast connection handoff. FIG. 2 illustrates a detailed flowchart of the method for real time seamless IP multicast connection handoff. The method (100) for real time seamless IP multicast connection handoff from a network interface of a current network to a network interface of a new network comprises activating the network interface of the new network (102), determining a delay duration for seamless IP multicast connection handoff (104), receiving a plurality of IP packets on the network interface of the new network (106) and de-activating the network interface of the current network upon expiration of the delay duration (108).

According to the embodiments of the present invention, the method (100) for real time seamless IP multicast connection handoff is independent of any mobility protocol, for instance MIP and SIP, implemented on the current network and the new network.

However, SIP may be implemented to perform user authentication, accounting and sharing of mobility sessions, such as video sessions between peer users. This feature of being independent of any mobility protocol renders the current network and the new network free from and not bounded to any specific network infrastructure.

The real time seamless IP multicast connection handoff may be triggered manually or automatically in order to invoke the real time seamless IP multicast connection handoff by activating the network interface of the new network (102). The manual trigger includes a user depressing a predetermined key, for instance a network switching key on the mobile node to invoke the real time seamless IP multicast connection handoff to alternative new networks besides the current network. On the other hand, the automatic trigger includes the incorporation of a signal analysis module, for instance a Received Signal Strength Indication (RSSI) analysis module to detect the signal degradation of the current network, and discover alternative new networks by consulting an information server. Once the real time seamless IP multicast connection handoff has been triggered, the network interface of the new network (102) is activated. This includes identifying the new network (202) based on a priority setting of a plurality of network interfaces, requesting an IP address (204) of the network interface of the identified new network and subscribing to a multicast group (206) of the identified new network.

The priority setting of the plurality of network interfaces on the mobile node is defined in a policy file. For instance, a user may configure an Ethernet interface with the highest priority, followed by a WiFi interface and a 3G interface. The network interface of the current network is also identified in the policy file and is denoted as the "old_interface". Upon identifying the new network (202), the IP address (204) of the network interface of the identified new network, denoted as the "new_interface", is requested from a Dynamic Host Configuration Protocol (DHCP) server. The "newjnterface" is then activated by subscribing to the multicast group (206) by sending a subscription request to the specific address of the multicast group.

Upon activating the "newjnterface", the delay duration for seamless IP multicast connection handoff is determined and simultaneously the plurality of IP packets or data packets are received on the network interface of the new network, which is the "newjnterface". The plurality of IP packets or data packets, such as video data that are received on the network interface of the new network (106), which is the "newjnterface" are written directly onto a buffer for play out (210). The delay duration for seamless IP multicast connection handoff (104) is determined by establishing the delay duration based on a predetermined parameter to ensure seamless IP multicast connection handoff (208). During the delay duration, the plurality of IP packets or data packets are received on the network interface of the current network, which is the "oldjnterface" and the network interface of the new network, which is the "newjnterface".

In one embodiment of the present invention, the predetermined parameter is a variable based on an algorithm that considers the IP packet or data packet frame size, frame rate as well as the current throughput of the connectivity in order to determine the delay duration value according to the following:

Delay Duration = ( Frame Size * Frame Rate ) / Current Throughput

In another embodiment of the present invention, where an even smoother multicast connection handoff or faster multicast connection handoff is required, the predetermined parameter is a constant value that may be configured by the user depending on the degradation experienced during the mobile sessions. In this case, the delay duration value is determined according to the following: Delay Duration = Delay Duration + ( +/- Constant )

The real time seamless IP multicast connection handoff of the present invention is concluded by de-activating the network interface of the current network, which is the "oldjnterface". The de-activation of the "oldjnterface" is performed upon expiration of the delay duration. This de-activation includes unsubscribing to a multicast group (214) of the current network, which is the "oldjnterface", by sending a un-subscription request to the specific address of the multicast group.

Upon completion of the real time seamless IP multicast connection handoff, the IP packets or data packets, are received on the activated "newjnterface" and the

"oldjnterface" is deactivated after the delay duration. However, as long as the delay duration does not expire, the IP packets or data packets are received on both the "old_interface" and the "newjnterface". The delay duration that is determined ensures transparent real time seamless IP multicast connection handoff such that the user experiences minimal or no degradation during the mobile sessions.