EP2401878A2

EP2401878A2 - Method for use in mobility hand-off between base stations

Info

Publication number: EP2401878A2
Application number: EP10746490A
Authority: EP
Inventors: Mohd Ariff Abdullah; Mohd Nor Izlan Mohd Nordin; Nor Azrishahril Aris; Mohsen Baratvand
Original assignee: Mimos Bhd
Current assignee: Mimos Bhd
Priority date: 2009-02-25
Filing date: 2010-02-24
Publication date: 2012-01-04
Also published as: EP2401878A4; WO2010098655A2; CN102415143B; MY150363A; WO2010098655A3; CN102415143A

Abstract

The present invention relates to a method for use in a hand-off process between base stations, preferably Wifi/WiMAX base stations. The primary steps include arranging the subnet for each base station in a predetermined sequence and thus predicting the most possible subnet prefix of the network that a node would attach next. By way of predicting the care-of-addresses assigned by the new network, hand-off process can be expedited.

Description

METHOD FOR USE IN MOBILITY HAND-OFF BETWEEN BASE STATIONS

Field of Invention

The present invention relates to a method for use in a handover process between two networks, and more particularly to a method and system for facilitating in efficiency and ensuring smooth handover process between two different networks.

Background of Invention

Various services offered by telecos and service providers for users nowadays require reliable access of technologies, both fixed and mobile. In order to benefit from these services, users prefer or expect to be connected to the World Wide Web despite the change of venues or locations and at any time they desire.

Accordingly, the gradual and in -depth integration into the technology has enable new classes of technological capabilities in regards to providing mobility in connection for users. In order to materialize such connectivity, several protocols have been developed and thus configured for supporting mobile connectivity, or for providing mobility support for users. Following the above, one of the most compatible protocol for this exclusive purpose is the Mobile Internet Protocol version 6 (MIPv6). The primary role of this protocol, which is known as a subset to one of the most advanced Internet protocols,

Internet Protocol version 6 (IPv6) is to allow seamless connectivity between mobile nodes and with other networks. In other words, MIPv6 provides and maintain connectivity when devices or nodes are roaming or moving around between IP networks.

Network Mobility (NEMO), is an extension of MIPv6 where instead of devices and nodes roaming individually, all nodes come together under a mobile network and mobility will be handled by a Mobile Router (MR).

Briefly, when a mobile node joins a network, a network application protocol obtains configuration information based on said network. Such pertinent role can be carried out by the Dynamic Host Configuration Protocol (DHCP). Accordingly, the DHCP server sends an Internet Protocol (IP) address also commonly known as the care- of-address (CoA) which is obtained from an IP addresses pool. It is basically a temporary address specifically assigned for the node or device that has entered the network. The IP address is a unique address and belongs to the subnet that the node is residing in. This process is known to be time consuming, particularly when the network is serving a large pool of dynamic IP addresses and in presence of countless nodes constantly attaching and detaching from the same network. Such condition is rather common particularly for MIPv6 and NEMO. Due to this time consuming step, the handover process to maintain connectivity from one network to another is consequently delayed.

Although the Internet Control Message Protocol (ICMP) may serve as a more expedient and fairly faster protocol for providing users indications on the success and failure in connecting with IP networks in substitution to the conventional DHCP, it may not be fast enough to ensure immediate and smooth handover process.

Recognizing the aforementioned, the present invention has been accomplished to significantly alleviate the above discussed shortcoming during a handover process. It is of significant advantage for the related industry to provide a method that aids to accelerate handover process and thus provide immediate connectivity or attachment to a new network.

It is therefore the primary object of the present invention to provide a method for speeding up or accelerating the hand off process from one network to another, thus ensuring an almost instant connectivity thereafter when nodes are roaming between networks.

It is another object of the present invention to provide a method for eliminating the need to wait for IP address prior to a handover process from one network to another.

It is yet another object of the present invention to provide a method that implements the prediction of care-of-address (CoA) assigned by a new network or new attachment point and thus eliminates the necessity to wait for Dynamic Host Control Protocol (DHCP) message for an IP address.

It is a further object of the present invention to provide a method that allows the prediction of the subsequent care-of-address (CoA) by way of applying a systematic subnet division in a parent network during a handover process.

Further objects and advantages of the present invention may become apparent upon referring to the preferred embodiments of the present invention as shown in the accompanying drawings and as described in the following description.

Summary of Invention

The present invention relates to a method for use in a handover process between base stations, and each base station attached to at least one sub network, comprising the steps of : arranging each subnet in a predetermined sequence; predicting a subnet prefix of Internet Protocol (IP) address of the adjacent base station based on the arrangement of the subnet; predicting the secondary and tertiary addresses of the adjacent base station based on said subnet prefix; wherein the secondary address directs to a next base station and the tertiary address directs to a previous base station (S300); sending a ping packet to the next base station's IP address with the secondary address and the previous base station IP address with the tertiary address (S400); obtaining the care-of-address of the base station based on the predicted secondary and tertiary addresses (S500). Brief Description of the Drawings

The invention will be more understood with the accompanying drawings herein:

FIG 1 illustrates a typical hierarchical nature of networks;

FIG 2 illustrates the operational effect in accordance with a preferred embodiment of the present invention; and

FIG 3 illustrates the flow chart to reflect the operational effect in accordance with a preferred embodiment of the present invention.

Detailed Description of the Preferred Embodiments

In line with the above summary, the following description of a number of specific and alternative embodiments is provided to understand the inventive features of the present invention. It shall be apparent to one skilled in the art, however that this invention may be practiced without such specific details.

It is further noted that the exemplifications and standard procedures which may be provided herein within the description meant to better elucidate the operational effect and embodiments of the present invention and therefore should not be construed as limiting the scope of protection.

The present invention is developed to aid in accelerating the hand off process in Mobile IPv6 (MlPvό) and Network Mobility (NEMO) in the event that a mobile node or a mobile network moves from one network to another network so as to maintain connectivity.

Typically, and as seen in FIG 1, in IPv6 address allocation, major networks such as the Internet Service Providers (ISPs) have address ranges with 32-bit prefixes. It is often that an ISP divides the address range into subnets of 64-bit prefixes, thereby providing up to 2³² or 4,294,967,296 subnets. However, considering hierarchical nature of existing networks, the number of available subnets will be much smaller than that.

In one preferred embodiment of the present invention, the architecture of the ISP network consists of eight levels of subnets, the ISP still have 2²⁴ or 16,777,216 subnets at the leaves of the network tree. This amount is sufficient provide a unique subnet to each Wi-Fi/WiMax base station.

From the above, with 2²⁴ subnets available, a systematic approach is provided in arranging the subnet for each base station in sequence. For instance, in the event that there two other available networks, network 2 is arranged between network 1 and network 3. As the subnets of base stations are in sequence, the mobile node is able to predict the most possible subnet prefix of the network it would be attached to next. This therefore provides a fast network attachment, accelerated rather similar to conditions of nodes with predetermined static IP address.

FIG 2 and FIG 3 show the operational effect in accordance with the preferred embodiments of the present invention. It should be mentioned that although the operative explanation focuses on Mobile Router (MR) as the attachment entity of the network, the method of the present invention can be implemented with Mobile Nodes.

In the first stage, as seen in FIG 2 and FIG 3, a Mobile Router (MR) enters a network and attaches to a base station. It is understood that each network would comprise at least one base station, and thereby in the event that a node moves from one network to another network, a handover process to get connected to the new network is initiated. Handover of networks therefore entails handover of base stations.

Typically, the Mobile Router would acquire a care-of-address from the base station. However with the method of the present invention, said Mobile Router (MR) assumes a secondary and a tertiary addresses by using the predicted subnet prefix of the adjacent base stations (S300). As mentioned in one of the preceding paragraphs, such prediction is enabled with the aid of arranging the subnets of base stations in a predetermined sequence. The secondary address points to the next base station and the tertiary address points to the previous base station in the sequence. The constructions of these addresses are preferably done by converting MAC address into EUI-64 node identifier. The 64-bit identifier is thereby used as the suffixes of the IPv6 addresses. Each 64-bit predicted prefix with the 64-bit EUI-64 suffix is a globally unique IPv6 address that is valid in the adjacent network.

It is noted that in accordance with another preferred embodiment of the present invention, all the base stations share the same suffix. This advantage enables the MR to indicate and thus locate the base station's IP address amongst other entities within the network.

It can be seen in FIG 3 that during the detachment of the MR of the current network, the MR pings the next base station's IP address based on the secondary address and previous base station's IP address using tertiary addresses simultaneously with the preferred Time-to-Live (TTL) value of 1 (S400) to obtain the care-of-address. In this process, a testing step is performed, whereby a ping packet is sent to the next base station's IP address. The ping packets is expected to return a response within the TTL =

1. If this occurs, the secondary address is the care-of-address (S500) and the process is initiated all over wherein the MR creates a new set of secondary and tertiary address based on predicted adjacent subnets. Accordingly, with the TTL value of 1, not more than one base station returns a reply with one hop limit restriction can be assured. Accordingly, the present invention eliminates the hassle of waiting for the DHCP to obtain the IP address from the network, and thus accelerate the hand-off process from one network to another network.

While the above provides a complete disclosure of the preferred embodiments of the present invention, various modifications, alternate constructions and equivalents may be employed without departing from the objective and scope of invention. The application is neither intended to limit its scope in any way.

Claims

1. A method for use in a handover process between base stations, and each base station attached to at least one sub network, comprising the steps of :

arranging each subnet in a predetermined sequence;

predicting a subnet prefix of Internet Protocol (IP) address of the adjacent base station based on the arrangement of the subnet;

predicting the secondary and tertiary addresses of the adjacent base station based on said subnet prefix; wherein the secondary address directs to a next base station and the tertiary address directs to a previous base station (S300);

obtaining the care-of-address of the base station based on the predicted secondary and tertiary addresses (S500).

2. The method as claimed in Claim 1 wherein the obtaining a care-of-address further comprises sending a ping packet to the next base station's IP address with the secondary address and the previous base station IP address with the tertiary address (S400).

3. The method as claimed in Claims 1 to 2 wherein the sending a ping packet to he next base station's step further comprising the step of receiving a response within the Time to Live (TTL) value of 1.

4. The method as claimed in Claims 1 to 3 wherein if a response is received within TTL=I upon sent the ping packet to the next base station's IP address, the secondary address will be the care-of-address.

5. The method as claimed in Claim 1 to 4 wherein the construction of these addresses is done by converting MAC address into EUI-64 node identifier.

6. The method as claimed in Claim 1 to 5 wherein the base stations share the same suffix.

7. The method as claimed in Claim 1 to 6 wherein the method is used for MIPv6 and NEMO.

8. The method as claimed in Claim 1 to 7 wherein the method is used for Wi- Fi/WiMAX base stations.

9. The method as claimed in Claim 1 to 8 wherein the method is used for mobility in the same network.